Clinical Focus

  • Cancer > Cutaneous (Dermatologic) Oncology
  • Cancer > Radiation Oncology
  • Radiation Oncology
  • Radiation Therapy
  • Head&Neck Cancer
  • Lung Cancers
  • Sarcoma

Academic Appointments

Administrative Appointments

  • Director, Radiation Oncology Medical Student Clerkship (2014 - Present)

Honors & Awards

  • Educator of the Year, Association of Residents in Radiation Oncology (2011)

Professional Education

  • Medical Education:University of Hawaii (2002) HI
  • Internship:University of Hawaii (2003) HI
  • Board Certification: Radiation Oncology, American Board of Radiology (2009)
  • Residency:Stanford - Radiation Oncology (2007) CA

Research & Scholarship

Clinical Trials

  • Modified Dakin's Solution in Reducing Radiation-Induced Dermatitis in Patients With Head and Neck Cancer Undergoing Radiation Therapy Recruiting

    This randomized phase III trial studies how well modified Dakin's solution works in reducing radiation-induced dermatitis, a common skin reaction to radiation therapy, in patients with head and neck cancer undergoing radiation therapy. Modified Dakin's solution may reduce inflammation in the body, which may prevent or reduce dermatitis after radiation therapy.

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  • Surgery With or Without Internal Radiation Therapy Compared With Stereotactic Body Radiation Therapy in Treating Patients With High-Risk Stage I Non-Small Cell Lung Cancer Not Recruiting

    RATIONALE: Surgery with or without internal radiation therapy may be an effective treatment for non-small cell lung cancer. Internal radiation uses radioactive material placed directly into or near a tumor to kill tumor cells. Stereotactic body radiation therapy may be able to send x-rays directly to the tumor and cause less damage to normal tissue. It is not yet known whether stereotactic body radiation therapy is more effective than surgery with or without internal radiation therapy in treating non-small cell lung cancer. PURPOSE: This randomized phase III trial is studying how well surgery with or without internal radiation therapy works compared with stereotactic body radiation therapy in treating patients with high-risk stage IA or stage IB non-small cell lung cancer.

    Stanford is currently not accepting patients for this trial. For more information, please contact Lisa Zhou, (650) 736 - 4112.

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  • Novel Serum Markers for Monitoring Response to Anti-Cancer Therapy Recruiting

    The purpose of this study is to measure the levels of serum proteins and other biomarkers in cancer patients and in patients suspected of having cancer. We believe that some of these markers may be useful for confirming the diagnosis or for selecting patients for specific types of cancer therapies. These markers may also help to predict response to therapy, relapse after therapy, and survival after therapy.

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  • Manuka Honey in Preventing Esophagitis-Related Pain in Patients Receiving Chemotherapy and Radiation Therapy For Lung Cancer Not Recruiting

    RATIONALE: Manuka honey may prevent or reduce esophagitis-related pain caused by chemotherapy and radiation therapy. It is not yet known whether Manuka honey is more effective than standard care in preventing pain. PURPOSE: This randomized phase II clinical trial is studying Manuka honey to see how well it works in preventing esophagitis-related pain in patients receiving chemotherapy and radiation therapy for lung cancer.

    Stanford is currently not accepting patients for this trial. For more information, please contact Laura Gable, (650) 736 - 0798.

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  • Radiation Therapy in Treating Patients With Extensive Stage Small Cell Lung Cancer Not Recruiting

    RATIONALE: Radiation therapy uses high energy x-rays to kill tumor cells. This may be an effective treatment for extensive stage small cell lung cancer. PURPOSE: This randomized phase II trial is comparing how well radiation therapy to the brain works when given with or without radiation therapy to other areas of the body in treating patients with extensive stage small cell lung cancer.

    Stanford is currently not accepting patients for this trial. For more information, please contact Laura Gable, (650) 736 - 0798.

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  • Reduced-Dose Intensity-Modulated Radiation Therapy With or Without Cisplatin in Treating Patients With Advanced Oropharyngeal Cancer Recruiting

    This randomized phase II trial studies how well modestly reduced-dose intensity-modulated radiation therapy (IMRT) with or without cisplatin works in treating patients with oropharyngeal cancer that has spread to other places in the body (advanced). Radiation therapy uses high energy x rays to kill tumor cells. Drugs used in chemotherapy, such as cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. It is not yet known whether IMRT is more effective with or without cisplatin in treating patients with oropharyngeal cancer.

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  • Study of Positron Emission Tomography and Computed Tomography in Guiding Radiation Therapy in Patients With Stage III Non-small Cell Lung Cancer Recruiting

    This randomized phase II trial studies how well positron emission tomography (PET)/computed tomography (CT)-guided radiation therapy works compared to standard radiation therapy in treating patients with stage III non-small cell lung cancer. Radiation therapy uses high-energy x-rays to kill tumor cells. Using imaging procedures, such as PET and CT scans, to guide the radiation therapy, may help doctors deliver higher doses directly to the tumor and cause less damage to healthy tissue.

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  • Individualized Treatment in Treating Patients With Stage II-IVB Nasopharyngeal Cancer Based on EBV DNA Recruiting

    There are two study questions we are asking in this randomized phase II/III trial based on a blood biomarker, Epstein Barr virus (EBV) deoxyribonucleic acid (DNA) for locoregionally advanced non-metastatic nasopharyngeal cancer. All patients will first undergo standard concurrent chemotherapy and radiation therapy. When this standard treatment is completed, if there is no detectable EBV DNA in their plasma, then patients are randomized to either standard adjuvant cisplatin and fluorouracil chemotherapy or observation. If there is still detectable levels of plasma EBV DNA, patients will be randomized to standard cisplatin and fluorouracil chemotherapy versus gemcitabine and paclitaxel. Radiation therapy uses high energy x rays to kill tumor cells. Drugs used in chemotherapy, such as cisplatin, fluorouracil, gemcitabine hydrochloride, and paclitaxel work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. It is not yet known whether giving cisplatin and fluorouracil is more effective than gemcitabine hydrochloride and paclitaxel after radiation therapy in treating patients with nasopharyngeal cancer.

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  • Imaging and Biomarkers of Hypoxia in Solid Tumors Recruiting

    We hope to find safer, noninvasive methods for measuring tumor hypoxia. Hypoxia, meaning a lack of oxygen, has been associated strongly with a wide range of human cancers. Hypoxia occurs when tumor growth exceeds the ability of blood vessels to supply the tumor with oxygenated blood. It is currently understood that hypoxic tumors are more aggressive. Current methods for measuring hypoxia include invasive procedures such as tissue biopsy, or insertion of an electrode into the tumor. EF5-PET may be a non-invasive way to make this measurement.

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  • Radiation Therapy With Cisplatin, Docetaxel, or Cetuximab After Surgery in Treating Patients With Stage III-IV Squamous Cell Head and Neck Cancer Not Recruiting

    This randomized phase II/III trial studies how well radiation therapy works when given together with cisplatin compared to docetaxel or cetuximab and docetaxel after surgery in treating patients with stage III-IV squamous cell head and neck cancer. Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. Drugs used in chemotherapy, such as cisplatin and docetaxel, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Monoclonal antibodies, such as cetuximab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or transmit tumor killing molecules to them. It is not yet known whether radiation therapy is more effective when given with cisplatin, docetaxel, or cetuximab and docetaxel.

    Stanford is currently not accepting patients for this trial. For more information, please contact Polly Young , 650-497-7499.

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  • Radiation Therapy With or Without Chemotherapy in Treating Patients With High-Risk Malignant Salivary Gland Tumors That Have Been Removed By Surgery Not Recruiting

    RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Drugs used in chemotherapy, such as cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. It is not yet known whether radiation therapy is more effective when given together with chemotherapy or alone after surgery in treating salivary gland tumors. PURPOSE: This randomized phase II trial is studying radiation therapy with or without chemotherapy to see how well it works in treating patients with high-risk malignant salivary gland tumors that have been removed by surgery.

    Stanford is currently not accepting patients for this trial. For more information, please contact Polly Young, 650-497-7499.

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  • Feasibility of IMRT Modulation to Account for Scattered Radiation From Dental Fillings in Head and Neck Cancer Not Recruiting

    The main objective of this study is to determine the feasibility of optimizing the IMRT treatment plan based on dosimeter measurements of mucosal radiation dose adjacent to the dental fillings to reduce such dose to < 35 Gy without compromising tumor coverage and/or increasing the dose to the remaining oral cavity or nearby parotid glands.

    Stanford is currently not accepting patients for this trial. For more information, please contact Cato Chan, 650-724-4606.

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All Publications

  • A prospective study of electronic quality of life assessment using tablet devices during and after treatment of head and neck cancers ORAL ONCOLOGY Pollom, E. L., Wang, E., Bui, T. T., Ognibene, G., von Eyben, R., Divi, V., Sunwoo, J., Kaplan, M., Colevas, A. D., Le, Q., Hara, W. Y. 2015; 51 (12): 1132-1137


    Electronic data collection is increasingly used for quality of life (QOL) assessments in the field of oncology. It is important to assess the feasibility of these new data capture technologies.Patients at our institution who were 18years or older with a pathological diagnosis of head and neck cancer were prospectively enrolled. Each patient completed two questionnaires [EORTC-QLQ-C30 and EORTC-QLQ-H&N35] administered on a touch-screen tablet device (iPad™) at initial consult, during treatment, at the completion of treatment and at each subsequent follow up visit for one year after treatment.A total of 50 patients were included in this study. Although all patients completed the surveys at the initial consult, 86% of initially enrolled patients completed surveys at the end of radiation treatment, and 48% of initially enrolled patients completed surveys by the fourth follow-up visit. Average time to complete the survey for all patients over all time points was 9.8min (standard deviation 6.1). Age as a continuous variable was significantly associated with time for survey completion (p<0.001), with older age associated with longer survey completion times.QOL assessment using tablet devices in head and neck cancer patients is feasible, but may be more challenging in elderly patients. Patients ⩾70years old may benefit from more assistance with electronic forms and should be allotted more time for completing tablet-based QOL surveys.

    View details for DOI 10.1016/j.oraloncology.2015.10.003

    View details for Web of Science ID 000366534000017

  • Concurrent Vismodegib and Radiotherapy for Recurrent, Advanced Basal Cell Carcinoma. JAMA dermatology Pollom, E. L., Bui, T. T., Chang, A. L., Colevas, A. D., Hara, W. Y. 2015; 151 (9): 998-1001


    Vismodegib is a targeted agent recently approved for treating patients who develop recurrent or locally advanced basal cell carcinoma (BCC), and will inevitably be integrated into existing therapy for advanced BCC as it becomes increasingly used. Improved understanding of how vismodegib interacts with other treatment modalities, including radiotherapy, would help optimize multidisciplinary therapy and clinical outcomes.We report 2 cases of recurrent, advanced BCC treated from April 1, 2012, through October 31, 2014, with concurrent radiotherapy and vismodegib. Concurrent treatment appeared to be well tolerated and efficacious, with both patients having no evidence of progressive disease at last follow-up.We found that the combination of vismodegib and radiotherapy is feasible for patients with recurrent or locally advanced BCC and that combined use of currently available therapies for advanced BCC warrants further prospective study.

    View details for DOI 10.1001/jamadermatol.2015.0326

    View details for PubMedID 25874733

  • Combining immunotherapy with radiation for the treatment of glioblastoma. Journal of neuro-oncology Chow, K. K., Hara, W., Lim, M., Li, G. 2015; 123 (3): 459-464


    Glioblastoma is a devastating cancer with universally poor outcomes in spite of current standard multimodal therapy. Immunotherapy is an attractive new treatment modality given its potential for exquisite specificity and its favorable side effect profile; however, clinical trials of immunotherapy in GBM have thus far shown modest benefit. Optimally combining radiation with immunotherapy may be the key to unlocking the potential of both therapies given the evidence that radiation can enhance anti-tumor immunity. Here we review this evidence and discuss considerations for combined therapy.

    View details for DOI 10.1007/s11060-015-1762-9

    View details for PubMedID 25877468

  • Stereotactic ablative radiotherapy (SABR) for treatment of central and ultra-central lung tumors LUNG CANCER Chaudhuri, A. A., Tang, C., Binkley, M. S., Jin, M., Wynne, J. F., von Eyben, R., Hara, W. Y., Trakul, N., Loo, B. W., Diehn, M. 2015; 89 (1): 50-56


    Treatment of central and ultra-central lung tumors with stereotactic ablative radiotherapy (SABR) remains controversial due to risks of treatment-related toxicities compared with peripheral tumors. Here we report our institution's experience in treating central and ultra-central lung tumor patients with SABR.We retrospectively reviewed outcomes in 68 patients with single lung tumors, 34 central and 34 peripheral, all treated with SABR consisting of 50Gy in 4-5 fractions. Tumor centrality was defined per the RTOG 0813 protocol. We defined "ultra-central" tumors as those with GTV directly abutting the central airway.Median follow-up time was 18.4months and median overall survival was 38.1 months. Two-year overall survival was similar between ultra-central, central, and peripheral NSCLC (80.0% vs. 63.2% vs. 86.6%, P=0.62), as was 2-year local failure (0% vs. 10.0% vs. 16.3%, P=0.64). Toxicity rates were low and comparable between the three groups, with only two cases of grade 3 toxicity (chest wall pain), and one case of grade 4 toxicity (pneumonitis) observed. Patients with ultra-central tumors experienced no symptomatic toxicities over a median follow-up time of 23.6 months. Dosimetric analysis revealed that RTOG 0813 central airway dose constraints were frequently not achieved in central tumor treatment plans, but this did not correlate with increased toxicity rate.Patients with central and ultra-central lung tumors treated with SABR (50Gy in 4-5 fractions) experienced few toxicities and good outcomes, similar to patients with peripheral lung tumors.

    View details for DOI 10.1016/j.lungcan.2015.04.014

    View details for Web of Science ID 000356546300010

  • TU-AB-BRA-10: Prognostic Value of Intra-Radiation Treatment FDG-PET and CT Imaging Features in Locally Advanced Head and Neck Cancer. Medical physics Song, J., Cui, Y., Pollom, E., Durkee, B., Aggarwal, S., Bui, T., Le, Q., Loo, B., Hara, W., Li, R. 2015; 42 (6): 3588-?


    To predict response to radiation treatment using computational FDG-PET and CT images in locally advanced head and neck cancer (HNC).68 patients with State III-IVB HNC treated with chemoradiation were included in this retrospective study. For each patient, we analyzed primary tumor and lymph nodes on PET and CT scans acquired both prior to and during radiation treatment, which led to 8 combinations of image datasets. From each image set, we extracted high-throughput, radiomic features of the following types: statistical, morphological, textural, histogram, and wavelet, resulting in a total of 437 features. We then performed unsupervised redundancy removal and stability test on these features. To avoid over-fitting, we trained a logistic regression model with simultaneous feature selection based on least absolute shrinkage and selection operator (LASSO). To objectively evaluate the prediction ability, we performed 5-fold cross validation (CV) with 50 random repeats of stratified bootstrapping. Feature selection and model training was solely conducted on the training set and independently validated on the holdout test set. Receiver operating characteristic (ROC) curve of the pooled Result and the area under the ROC curve (AUC) was calculated as figure of merit.For predicting local-regional recurrence, our model built on pre-treatment PET of lymph nodes achieved the best performance (AUC=0.762) on 5-fold CV, which compared favorably with node volume and SUVmax (AUC=0.704 and 0.449, p<0.001). Wavelet coefficients turned out to be the most predictive features. Prediction of distant recurrence showed a similar trend, in which pre-treatment PET features of lymph nodes had the highest AUC of 0.705.The radiomics approach identified novel imaging features that are predictive to radiation treatment response. If prospectively validated in larger cohorts, they could aid in risk-adaptive treatment of HNC.

    View details for DOI 10.1118/1.4925515

    View details for PubMedID 26128812

  • A unifying probabilistic Bayesian approach to derive electron density from MRI for radiation therapy treatment planning PHYSICS IN MEDICINE AND BIOLOGY Gudur, M. S., Hara, W., Le, Q., Wang, L., Xing, L., Li, R. 2014; 59 (21): 6595-6606
  • A unifying probabilistic Bayesian approach to derive electron density from MRI for radiation therapy treatment planning. Physics in medicine and biology Gudur, M. S., Hara, W., Le, Q., Wang, L., Xing, L., Li, R. 2014; 59 (21): 6595-6606


    MRI significantly improves the accuracy and reliability of target delineation in radiation therapy for certain tumors due to its superior soft tissue contrast compared to CT. A treatment planning process with MRI as the sole imaging modality will eliminate systematic CT/MRI co-registration errors, reduce cost and radiation exposure, and simplify clinical workflow. However, MRI lacks the key electron density information necessary for accurate dose calculation and generating reference images for patient setup. The purpose of this work is to develop a unifying method to derive electron density from standard T1-weighted MRI. We propose to combine both intensity and geometry information into a unifying probabilistic Bayesian framework for electron density mapping. For each voxel, we compute two conditional probability density functions (PDFs) of electron density given its: (1) T1-weighted MRI intensity, and (2) geometry in a reference anatomy, obtained by deformable image registration between the MRI of the atlas and test patient. The two conditional PDFs containing intensity and geometry information are combined into a unifying posterior PDF, whose mean value corresponds to the optimal electron density value under the mean-square error criterion. We evaluated the algorithm's accuracy of electron density mapping and its ability to detect bone in the head for eight patients, using an additional patient as the atlas or template. Mean absolute HU error between the estimated and true CT, as well as receiver operating characteristics for bone detection (HU > 200) were calculated. The performance was compared with a global intensity approach based on T1 and no density correction (set whole head to water). The proposed technique significantly reduced the errors in electron density estimation, with a mean absolute HU error of 126, compared with 139 for deformable registration (p = 2  ×  10(-4)), 283 for the intensity approach (p = 2  ×  10(-6)) and 282 without density correction (p = 5  ×  10(-6)). For 90% sensitivity in bone detection, the proposed method achieved a specificity of 86%, compared with 80, 11 and 10% using deformable registration, intensity and without density correction, respectively. Notably, the Bayesian approach was more robust against anatomical differences between patients, with a specificity of 62% in the worst case (patient), compared to 30% specificity in registration-based approach. In conclusion, the proposed unifying Bayesian method provides accurate electron density estimation and bone detection from MRI of the head with highly heterogeneous anatomy.

    View details for DOI 10.1088/0031-9155/59/21/6595

    View details for PubMedID 25321341

  • Salvage Treatment for Locally Recurrent Nasopharyngeal Carcinoma (NPC) AMERICAN JOURNAL OF CLINICAL ONCOLOGY-CANCER CLINICAL TRIALS Chen, C., Fee, W., Chen, J., Chan, C., Khong, B., Hara, W., Goffinet, D., Li, D., Quynh-Thu Le, Q. T. 2014; 37 (4): 327-331


    BACKGROUND:: It is important to determine the outcomes of retreatment in patients with locally recurrent nasopharyngeal carcinoma. METHODS:: We reviewed the records of patients treated for local recurrence at Stanford and Shantou Universities. The end points were local relapse-free survival (LRFS) and overall survival after retreatment. RESULTS:: Fifty-six patients from Stanford and 98 from Shantou qualified. For the Stanford patients, 33 had surgery alone (S group), 12 had surgery plus radiotherapy±chemotherapy (CMT group), and 22 had radiotherapy±chemotherapy (RT Stanford group). All Shantou patients received radiotherapy±chemotherapy (RT Shantou group). The 5-year LRFS rates were: 57% for S group, 25% for CMT group, 53% for RT Stanford group, and 41% for RT Shantou group (P>0.05) for rT1-2 tumors; they were 29% for S group, 25% for CMT group, 39% for RT Stanford group, and 9% for RT Shantou group for rT3-4 tumors (P>0.05). For RT patients, 5-year overall survival rates were 49% for Stanford and 25% for Shantou patients (P=0.026). CONCLUSIONS:: Similar and durable LRFS rates were attained for both S and RT groups when stratified by rT-stage.

    View details for DOI 10.1097/COC.0b013e318277d804

    View details for Web of Science ID 000340213200003

    View details for PubMedID 23275273

  • Radiotherapy for nonadenoid cystic carcinomas of major salivary glands AMERICAN JOURNAL OF OTOLARYNGOLOGY Chung, M. P., Tang, C., Chan, C., Hara, W. Y., Loo, B. W., Kaplan, M. J., Fischbein, N., Le, Q., Chang, D. T. 2013; 34 (5): 425-430


    PURPOSE: To report outcomes in patients treated with postoperative radiotherapy for nonadenoid cystic carcinomas of the major salivary glands. MATERIALS AND METHODS: From 1998-2011, 37 patients with nonadenoid cystic carcinomas of the major salivary gland underwent postoperative radiotherapy. The median radiation dose was 60Gy (range, 45-70Gy). TNM distribution included T1-2 (n=16, 44%), T3-T4 (n=21, 56%), N0 (n=19, 51%), and N+ (n=18, 49%). Histologies included adenocarcinoma (n=13, 35%), squamous cell carcinoma (n=8, 22%), mucoepidermoid carcinoma (n=8, 22%), and other (n=8, 21%). Median follow-up was 4.7years for all patients (range, 0.3-14.1years) and 5.0years for living patients (range, 1.2-12.2years). RESULTS: Five-year local-regional control, overall survival (OS), and cancer-specific survival (CSS) were 97%, 76%, and 84%. On univariate analysis, OS was significantly worse for patients ≥65years old (p=0.04). CSS was significantly worse for positive perineural invasion (p=0.02), extraparenchymal extension (p=0.04), and in patients who received no chemotherapy (p=0.02). Doses >60Gy was significantly worse for OS (p=0.003) and CSS (p=0.003), although these patients had higher TNM (>T2, p=0.01) and trended towards a higher rate of extraparenchymal extension (p=0.08). Four patients (11%) developed ≥grade 2 toxicities; 3 patients developed early toxicities and one patient developed late toxicities. CONCLUSIONS: Radiotherapy for salivary gland tumors provides excellent local-regional control when combined with surgery. Distant metastasis is the predominant pattern of failure, although chemotherapy seemed to improve cancer-specific survival.

    View details for DOI 10.1016/j.amjoto.2013.03.007

    View details for Web of Science ID 000324149400012

  • Stereotactic Radiosurgery for Retreatment of Gross Perineural Invasion in Recurrent Cutaneous Squamous Cell Carcinoma of the Head and Neck AMERICAN JOURNAL OF CLINICAL ONCOLOGY-CANCER CLINICAL TRIALS Tang, C., Fischbein, N. J., Murphy, J. D., Chu, K. P., Bavan, B., Dieterich, S., Hara, W., Kaplan, M. J., Colevas, A. D., Quynh-Thu Le, Q. T. 2013; 36 (3): 293-298


    : To report outcomes, failure patterns, and toxicity after stereotactic radiosurgery (SRS) for recurrent head and neck cutaneous squamous cell carcinoma with gross perineural invasion (GPNI).: Ten patients who received SRS as part of retreatment for recurrent head and neck cutaneous squamous cell carcinoma with GPNI were included. All patients exhibited clinical and radiologic evidence of GPNI before SRS. Previous treatments included surgery alone in 3 patients and surgery with adjuvant external beam radiotherapy (EBRT) in 7 patients. Retreatment included SRS alone in 2 and EBRT boosted with SRS in 8 patients. Magnetic resonance images were obtained every 3 to 6 months after SRS to track failure patterns.: At a median 22-month follow-up, the 2-year progression-free and overall survival rates were 20% and 50%, respectively. Seven patients exhibited local failures, all of which occurred outside both SRS and EBRT fields. Five local failures occurred in previously clinically uninvolved cranial nerves (CNs). CN disease spreads through 3 distinct patterns: among different branches of CN V; between CNs V and VII; and between V1 and CNs III, IV, and/or VI. Five patients experienced side effects potentially attributable to radiation.: Although there is excellent in-field control with this approach, the rate of out-of-field failures remains unacceptably high. We found that the majority of failures occurred in previously clinically uninvolved CNs often just outside treatment fields. Novel treatment strategies targeting this mode of perineural spread are needed.

    View details for DOI 10.1097/COC.0b013e3182468019

    View details for Web of Science ID 000319446500015

  • Impact of positron emission tomography/computed tomography surveillance at 12 and 24 months for detecting head and neck cancer recurrence. Cancer Ho, A. S., Tsao, G. J., Chen, F. W., Shen, T., Kaplan, M. J., Colevas, A. D., Fischbein, N. J., Quon, A., Le, Q., Pinto, H. A., Fee, W. E., Sunwoo, J. B., Sirjani, D., Hara, W., Yao, M. 2013; 119 (7): 1349-1356


    In head and neck cancer (HNC), 3-month post-treatment positron emission tomography (PET)/computed tomography (CT) reliably identifies persistent/recurrent disease. However, further PET/CT surveillance has unclear benefit. The impact of post-treatment PET/CT surveillance on outcomes is assessed at 12 and 24 months.A 10-year retrospective analysis of HNC patients was carried out with long-term serial imaging. Imaging at 3 months included either PET/CT or magnetic resonance imaging, with all subsequent imaging comprised of PET/CT. PET/CT scans at 12 and 24 months were evaluated only if preceding interval scans were negative. Of 1114 identified patients, 284 had 3-month scans, 175 had 3- and 12-month scans, and 77 had 3-, 12-, and 24-month scans.PET/CT detection rates in clinically occult patients were 9% (15 of 175) at 12 months, and 4% (3 of 77) at 24 months. No difference in outcomes was identified between PET/CT-detected and clinically detected recurrences, with similar 3-year disease-free survival (41% vs 46%, P = .91) and 3-year overall survival (60% vs 54%, P = .70) rates. Compared with 3-month PET/CT, 12-month PET/CT demonstrated fewer equivocal reads (26% vs 10%, P < .001). Of scans deemed equivocal, 6% (5 of 89) were ultimately found to be positive.HNC patients with negative 3-month imaging appear to derive limited benefit from subsequent PET/CT surveillance. No survival differences were observed between PET/CT-detected and clinically detected recurrences, although larger prospective studies are needed for further investigation.

    View details for DOI 10.1002/cncr.27892

    View details for PubMedID 23225544

  • Stereotactic Ablative Radiotherapy for Reirradiation of Locally Recurrent Lung Tumors JOURNAL OF THORACIC ONCOLOGY Trakul, N., Harris, J. P., Le, Q., Hara, W. Y., Maxim, P. G., Loo, B. W., Diehn, M. 2012; 7 (9): 1462-1465


    Patients with thoracic tumors that recur after irradiation currently have limited therapeutic options. Retreatment using stereotactic ablative radiotherapy (SABR) is appealing for these patients because of its high conformity but has not been studied extensively. Here we report our experience with SABR for lung tumors in previously irradiated regions.We conducted a retrospective study of patients with primary lung cancer or metastatic lung tumors treated with SABR. We identified 17 such tumors in 15 patients and compared their outcomes with those of a cohort of 135 previously unirradiated lung tumors treated with SABR during the same time period.Twelve-month local control (LC) for retreated tumors was 65.5%, compared with 92.1% for tumors receiving SABR as initial treatment. Twelve-month LC was significantly worse for reirradiated tumors in which the time interval between treatments was 16 months or less (46.7%), compared with those with longer intertreatment intervals (87.5%). SABR reirradiation did not lead to significant increases in treatment-related toxicity.SABR for locally recurrent lung tumors arising in previously irradiated fields seems to be feasible and safe for appropriately selected patients. LC of retreated lesions was significantly lower, likely owing to the lower doses used for retreatment. Shorter time to retreatment was associated with increased risk of local failure, suggesting that these tumors may be particularly radioresistant. Our findings suggest that dose escalation may improve LC while maintaining acceptable levels of toxicity for these patients.

    View details for DOI 10.1097/JTO.0b013e31825f22ce

    View details for Web of Science ID 000308073300024

    View details for PubMedID 22895143

  • Evaluation of a metal artifact reduction technique in tonsillar cancer delineation. Practical radiation oncology Abelson, J. A., Murphy, J. D., Wiegner, E. A., Abelson, D., Sandman, D. N., Boas, F. E., Hristov, D., Fleischmann, D., Daly, M. E., Chang, D. T., Loo, B. W., Hara, W., Le, Q. 2012; 2 (1): 27-34


    Metal artifacts can degrade computed tomographic (CT) simulation imaging and impair accurate delineation of tumors for radiation treatment planning purposes. We investigated a Digital Imaging and Communications in Medicine-based metal artifact reduction technique in tonsillar cancer delineation.Eight patients with significant artifact and tonsil cancer were evaluated. Each patient had a positron emission tomography (PET)-CT and a contrast-enhanced CT obtained at the same setting during radiotherapy simulation. The CTs were corrected for artifact using the metal deletion technique (MDT). Two radiation oncologists independently delineated primary gross tumor volumes (GTVs) for each patient on native (CTnonMDT), metal corrected (CTMDT), and reference standard (CTPET/nonMDT) imaging, 1 week apart. Mixed effects models were used to determine if differences among GTVs were statistically significant. Two diagnostic radiologists and 2 radiation oncologists independently qualitatively evaluated CTs for each patient. Ratings were on an ordinal scale from -3 to +3, denoting that CTMDT was markedly, moderately, or slightly worse or better than CTnonMDT. Scores were compared with a Wilcoxon signed-rank test.The GTVPET/nonMDT were significantly smaller than GTVnonMDT (P = .004) and trended to be smaller than GTVMDT (P = .084). The GTVnonMDT and GTVMDT were not significantly different (P = .93). There was no significant difference in the extent to which GTVnonMDT or GTVMDT encompassed GTVPET/nonMDT (P = .33). In the subjective assessment of image quality, CTMDT did not significantly outperform CTnonMDT. In the majority of cases, the observer rated the CTMDT equivalent to (53%) or slightly superior (41%) to the corresponding CTnonMDT.The MTD modified images did not produce GTVMDT that more closely reproduced GTVPET/nonMDT than did GTVnonMDT. Moreover, the MTD modified images were not judged to be significantly superior when compared to the uncorrected images in terms of subjective ability to visualize the tonsilar tumors. This study failed to demonstrate value of the adjunctive use of a CT corrected for artifacts in the tumor delineation process. Artifacts do make tumor delineation challenging, and further investigation of other body sites is warranted.

    View details for DOI 10.1016/j.prro.2011.06.004

    View details for PubMedID 24674033

  • Intensity-Modulated Radiation Therapy Versus Conventional Radiation Therapy for Squamous Cell Carcinoma of the Anal Canal CANCER Bazan, J. G., Hara, W., Hsu, A., Kunz, P. A., Ford, J., Fisher, G. A., Welton, M. L., Shelton, A., Kapp, D. S., Koong, A. C., Goodman, K. A., Chang, D. T. 2011; 117 (15): 3342-3351


    The purpose of this study was to compare outcomes in patients with anal canal squamous cell carcinoma (SCCA) who were treated with definitive chemoradiotherapy by either intensity-modulated radiation therapy (IMRT) or conventional radiotherapy (CRT).Forty-six patients who received definitive chemoradiotherapy from January 1993 to August 2009 were included. Forty-five patients received 5-fluorouracil with mitomycin C (n = 39) or cisplatin (n = 6). Seventeen (37%) were treated with CRT and 29 (63%) with IMRT. The median dose was 54 Gy in both groups. Median follow-up was 26 months (CRT) and 32 months (IMRT). T3-T4 stage (P = .18) and lymph node-positive disease (P = .6) were similar between groups.The CRT group required longer treatment duration (57 days vs 40 days, P < .0001), more treatment breaks (88% vs 34.5%, P = .001), and longer breaks (12 days vs 1.5 days, P < .0001) than patients treated with IMRT. Eleven (65%) patients in the CRT group experienced grade >2 nonhematologic toxicity compared with 6 (21%) patients in the IMRT group (P = .003). The 3-year overall survival (OS), locoregional control (LRC), and progression-free survival were 87.8%, 91.9%, and 84.2%, respectively, for the IMRT groups and 51.8%, 56.7%, and 56.7%, respectively, for the CRT group (all P < .01). On multivariate analysis, T stage, use of IMRT, and treatment duration were associated with OS, and T stage and use of IMRT were associated with LRC.The use of IMRT was associated with less toxicity, reduced need for treatment breaks, and excellent LRC and OS compared with CRT in patients with SCCA of the anal canal.

    View details for DOI 10.1002/cncr.25901

    View details for Web of Science ID 000293103800008

    View details for PubMedID 21287530

  • Tumor Volume as a Potential Imaging-Based Risk-Stratification Factor in Trimodality Therapy for Locally Advanced Non-small Cell Lung Cancer JOURNAL OF THORACIC ONCOLOGY Kozak, M. M., Murphy, J. D., Schipper, M. L., Donington, J. S., Zhou, L., Whyte, R. I., Shrager, J. B., Hoang, C. D., Bazan, J., Maxim, P. G., Graves, E. E., Diehn, M., Hara, W. Y., Quon, A., Quynh-Thu Le, Q. T., Wakelee, H. A., Loo, B. W. 2011; 6 (5): 920-926


    The role of trimodality therapy for locally advanced non-small cell lung cancer (NSCLC) continues to be defined. We hypothesized that imaging parameters on pre- and postradiation positron emission tomography (PET)-computed tomography (CT) imaging are prognostic for outcome after preoperative chemoradiotherapy (CRT)/resection/consolidation chemotherapy and could help risk-stratify patients in clinical trials.We enrolled 13 patients on a prospective clinical trial of trimodality therapy for resectable locally advanced NSCLC. PET-CT was acquired for radiation planning and after 45 Gy. Gross tumor volume (GTV) and standardized uptake value were measured at pre- and post-CRT time points and correlated with nodal pathologic complete response, loco-regional and/or distant progression, and overall survival. In addition, we evaluated the performance of automatic deformable image registration (ADIR) software for volumetric response assessment.All patients responded with average total GTV reductions after 45 Gy of 43% (range: 27-64%). Pre- and post-CRT GTVs were highly correlated (R² = 0.9), and their respective median values divided the patients into the same two groups. ADIR measurements agreed closely with manually segmented post-CRT GTVs. Patients with GTV ? median (137 ml pre-CRT and 67 ml post-CRT) had 3-year progression-free survival (PFS) of 14% versus 75% for GTV less than median, a significant difference (p = 0.049). Pre- and post-CRT PET-standardized uptake value did not correlate significantly with pathologic complete response, PFS, or overall survival.Preoperative CRT with carboplatin/docetaxel/45 Gy resulted in excellent response rates. In this exploratory analysis, pre- and post-CRT GTV predicted PFS in trimodality therapy, consistent with our earlier studies in a broader cohort of NSCLC. ADIR seems robust enough for volumetric response assessment in clinical trials.

    View details for DOI 10.1097/JTO.0b013e31821517db

    View details for Web of Science ID 000289554100012

    View details for PubMedID 21774104

  • Marked Tumor Response and Fatal Hemoptysis During Radiation for Lung Cancer in a Human Immunodeficiency Virus-Positive Patient Taking Nelfinavir JOURNAL OF THORACIC ONCOLOGY Chapman, C. H., Shen, J., Filion, E. J., Tran, P. T., Hara, W., Asuncion, A., Marko, D., Wakelee, H., Berry, G. J., Dimmick, K. W., Loo, B. W., Green, J. 2009; 4 (12): 1587-1589

    View details for Web of Science ID 000272095500025

    View details for PubMedID 20009915



    Nasopharyngeal carcinoma (NPC) has a bimodal age distribution. In contrast to the adult variant, little is known about the juvenile form. This study examined the treatment results between adult (aNPC) and juvenile NPC (jNPC) patients for future treatment considerations in jNPC.The jNPC population included 53 patients treated at two institutions between 1972 and 2004. The aNPC population included 84 patients treated at one institution. The patients had received a median dose of 66 Gy of external beam radiotherapy and 72% underwent chemotherapy. The mean follow-up for surviving patients was 12.6 years for jNPC and 6.6 years for aNPC.The jNPC patients presented with more advance stages than did the aNPC patients (92% vs. 67% Stage III-IV, p = .006). However, jNPC patients had significantly better overall survival (OS) than did aNPC patients. The 5-year OS rate was 71% for jNPC and 58% for aNPC (p = .03). The jNPC group also demonstrated a trend for greater relapse-free survival than the aNPC group (5-year relapse-free survival rate, 69% vs. 49%; p = .056). The pattern of failure analysis revealed that the jNPC patients had greater locoregional control and freedom from metastasis but the differences were not statistically significant. Univariate analysis for OS revealed that age group, nodal classification, and chemotherapy use were significant prognostic factors. Age group remained significant for OS on multivariate analysis, after adjusting for N classification and treatment.Despite more advance stage at presentation, jNPC patients had better survival than did aNPC patients. Future treatment strategies should take into consideration the long-term complications in these young patients.

    View details for DOI 10.1016/j.ijrobp.2008.12.030

    View details for Web of Science ID 000271489600017

    View details for PubMedID 19327901

  • CYBERKNIFE FOR BRAIN METASTASES OF MALIGNANT MELANOMA AND RENAL CELL CARCINOMA NEUROSURGERY Hara, W., Tran, P., Li, G., Su, Z., Puataweepong, P., Adler, J. R., Soltys, S. G., Chang, S. D., Gibbs, I. C. 2009; 64 (2): A26-A32


    To evaluate the efficacy of CyberKnife (Accuray, Inc., Sunnyvale, CA) stereotactic radiosurgery (SRS) for patients with brain metastases of malignant melanoma and renal cell carcinoma.We conducted a retrospective review of all patients treated by image-guided radiosurgery at our institution between March 1999 and December 2005. Sixty-two patients with 145 brain metastases of renal cell carcinoma or melanoma were identified.The median follow-up period was 10.5 months. Forty-four patients had malignant melanoma, and 18 patients had renal cell carcinoma. The median age was 57 years, and patients were classified as recursive partitioning analysis Class 1 (6 patients), 2 (52 patients) or 3 (4 patients). Thirty-three patients had been treated systemically with either chemotherapy or immunotherapy, and 33 patients were taking corticosteroids at the time of treatment. The mean tumor volume was 1.47 mL (range, 0.02-35.7 mL), and the mean prescribed dose was 20 Gy (range, 14-24 Gy). The median survival after SRS was 8.3 months. Actuarial survival at 6 and 12 months was 57 and 37%, respectively. On multivariate analysis, Karnofsky Performance Scale score (P < 0.01) and previous immunotherapy/clinical trial (P = 0.01) significantly affected overall survival. One-year intracranial progression-free survival was 38%, and local control was 87%. Intracranial control was impacted by whole-brain radiotherapy (P = 0.01), previous chemotherapy (P = 0.01), and control of the primary at the time of SRS (P = 0.02). Surgical resection had no effect on intracranial or local control. Radiographic evidence of radiation necrosis developed in 4 patients (6%).CyberKnife radiosurgery provided excellent local control with acceptable toxicity in patients with melanoma or renal cell brain metastases. Initial SRS alone appeared to be a reasonable option, as survival was dictated by systemic disease.

    View details for DOI 10.1227/01.NEU.0000339118.55334.EA

    View details for Web of Science ID 000262797700009

    View details for PubMedID 19165071



    To analyze the outcomes of and identify prognostic factors for patients treated with surgery and intraoperative radiotherapy (IORT) for locally advanced and recurrent soft-tissue sarcoma in adults from a single institution.We retrospectively reviewed 50 consecutive patients treated with IORT to 62 sites of disease. Primary sites included retroperitoneum-pelvis (78%), extremity (8%), and other (14%). Seventy percent of patients had recurrent disease failing prior surgery (70%) and/or radiation (32%). Mean disease-free interval (DFI) before IORT was 1.9 years (range, 2 weeks-5.4 years). The IORT was delivered with orthovoltage X-rays using individually sized beveled cone applicators. Clinical characteristics were as follows: mean tumor size, 10 cm (range, 1-25 cm); high-grade histologic subtype (72%); and mean dose, 1,159 cGy (range, 600-1,600 cGy). Postoperative radiation or chemotherapy was administered to 37% of IORT Sites and 32% of patients, respectively. Outcomes measured were infield control (IFC), locoregional control (LRC), distant metastasis-free survival (DMFS), disease-specific survival (DSS), and treatment-related complications. Mean and median follow-up of alive patients were 59 and 35 months, respectively.Kaplan-Meier 5-year IFC, LRC, DMFS, and DSS probabilities for the entire group were 55%, 26%, 51%, and 25%, respectively. Prognostic factors found to be significant (p < 0.05) on multivariate analysis were prior DFI and tumor size for LRC, extremity location and leiomyosarcoma histologic subtype for DMFS, and prior DFI for DSS. Our cohort had five Grade 3/4 complications associated with treatment or a 5-year Kaplan-Meier Grade 3/4 complication-free survival rate of 85%.IORT after tumor reductive surgery is well tolerated and seems to confer IFC in carefully selected patients.

    View details for DOI 10.1016/j.ijrobp.2008.02.012

    View details for Web of Science ID 000260592600026

    View details for PubMedID 18394818

  • Excellent local control with stereotactic radiotherapy boost after external beam radiotherapy in patients with nasopharyngeal carcinoma INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Hara, W., Loo, B. W., Goffinet, D. R., Chang, S. D., Adler, J. R., Pinto, H. A., Fee, W. E., Kaplan, M. J., Fischbein, N. J., Le, Q. 2008; 71 (2): 393-400


    To determine long-term outcomes in patients receiving stereotactic radiotherapy (SRT) as a boost after external beam radiotherapy (EBRT) for locally advanced nasopharyngeal carcinoma (NPC).Eight-two patients received an SRT boost after EBRT between September 1992 and July 2006. Nine patients had T1, 30 had T2, 12 had T3, and 31 had T4 tumors. Sixteen patients had Stage II, 19 had Stage III, and 47 had Stage IV disease. Patients received 66 Gy of EBRT followed by a single-fraction SRT boost of 7-15 Gy, delivered 2-6 weeks after EBRT. Seventy patients also received cisplatin-based chemotherapy delivered concurrently with and adjuvant to radiotherapy.At a median follow-up of 40.7 months (range, 6.5-144.2 months) for living patients, there was only 1 local failure in a patient with a T4 tumor. At 5 years, the freedom from local relapse rate was 98%, freedom from nodal relapse 83%, freedom from distant metastasis 68%, freedom from any relapse 67%, and overall survival 69%. Late toxicity included radiation-related retinopathy in 3, carotid aneurysm in 1, and radiographic temporal lobe necrosis in 10 patients, of whom 2 patients were symptomatic with seizures. Of 10 patients with temporal lobe necrosis, 9 had T4 tumors.Stereotactic radiotherapy boost after EBRT provides excellent local control for patients with NPC. Improved target delineation and dose homogeneity of radiation delivery for both EBRT and SRT is important to avoid long-term complications. Better systemic therapies for distant control are needed.

    View details for DOI 10.1016/j.ijrobp.2007.10.027

    View details for Web of Science ID 000255971100013

    View details for PubMedID 18164839

  • CyberKnife (R) robotic radiosurgery system for tumor treatment EXPERT REVIEW OF ANTICANCER THERAPY Hara, W., Soltys, S. G., Gibbs, I. C. 2007; 7 (11): 1507-1515


    Defined by its high level of accuracy and rapid radiation dose fall-off, radiosurgery has emerged as an effective radiation technique over the past few decades. Although it was once limited to conditions of the brain, head and neck regions, technological advances in computing and imaging have allowed the application of radiosurgery to conditions throughout the entire body. Using advanced imaging and robotics, the CyberKnife (Accuray, Inc., Sunnyvale, CA, USA) is one of few systems capable of delivering radiosurgery with exquisite accuracy to tumors, cancers and other conditions throughout the body. This review focuses on the development, technology, clinical efficacy and future directions of the CyberKnife.

    View details for DOI 10.1586/14737140.7-11.1507

    View details for Web of Science ID 000251444300009

    View details for PubMedID 18020920

  • Metabolic tumor burden predicts for disease progression and death in lung cancer INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Lee, P., Weerasuriya, D. K., Lavori, P. W., Quon, A., Hara, W., Maxim, P. G., Le, Q., Wakelee, H. A., Donington, J. S., Graves, E. E., Loo, B. W. 2007; 69 (2): 328-333


    In lung cancer, stage is an important prognostic factor for disease progression and survival. However, stage may be simply a surrogate for underlying tumor burden. Our purpose was to assess the prognostic value of tumor burden measured by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging.We identified 19 patients with lung cancer who had staging PET-CT scans before any therapy, and adequate follow-up (complete to time of progression for 18, and death for 15 of 19). Metabolically active tumor regions were segmented on pretreatment PET scans semi-automatically using custom software. We determined the relationship between times to progression (TTP) and death (OS) and two PET parameters: total metabolic tumor volume (MTV), and standardized uptake value (SUV).The estimated median TTP and OS for the cohort were 9.3 months and 14.8 months. On multivariate Cox proportional hazards regression analysis, an increase in MTV of 25 ml (difference between the 75th and 25th percentiles) was associated with increased hazard of progression and of death (5.4-fold and 7.6-fold), statistically significant (p = 0.0014 and p = 0.001) after controlling for stage, treatment intent (definitive or palliative), age, Karnofsky performance status, and weight loss. We did not find a significant relationship between SUV and TTP or OS.In this study, high tumor burden assessed by PET MTV is an independent poor prognostic feature in lung cancer, promising for stratifying patients in randomized trials and ultimately for selecting risk-adapted therapies. These results will need to be validated in larger cohorts with longer follow-up, and evaluated prospectively.

    View details for DOI 10.1016/j.ijrobp.2007.04.036

    View details for Web of Science ID 000249796100002

    View details for PubMedID 17869659

  • Long-term survivors using intraoperative radiotherapy for recurrent gynecologic malignancies INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Tran, P. T., Su, Z., Hara, W., Husain, A., Teng, N., Kapp, D. S. 2007; 69 (2): 504-511


    To analyze the outcomes of therapy and identify prognostic factors for patients treated with surgery followed by intraoperative radiotherapy (IORT) for gynecologic malignancies at a single institution.We performed a retrospective review of 36 consecutive patients treated with IORT to 44 sites with mean follow-up of 50 months. The primary site was the cervix in 47%, endometrium in 31%, vulva in 14%, vagina in 6%, and fallopian tubes in 3%. Previous RT had failed in 72% of patients, and 89% had recurrent disease. Of 38 IORT sessions, 84% included maximal cytoreductive surgery, including 18% exenterations. The mean age was 52 years (range, 30-74), mean tumor size was 5 cm (range, 0.5-12), previous disease-free interval was 32 months (range, 0-177), and mean IORT dose was 1,152 cGy (range, 600-1,750). RT and systemic therapy after IORT were given to 53% and 24% of the cohort, respectively. The outcomes measured were locoregional control (LRC), distant metastasis-free survival (DMFS), disease-specific survival (DSS), and treatment-related complications.The Kaplan-Meier 5-year LRC, DMFS, and DSS probability for the whole group was 44%, 51%, and 47%, respectively. For cervical cancer patients, the Kaplan-Meier 5-year LRC, DMFS, and DSS estimate was 45%, 60%, and 46%, respectively. The prognostic factors found on multivariate analysis (p

    View details for DOI 10.1016/j.ijrobp.2007.03.021

    View details for Web of Science ID 000249796100026

    View details for PubMedID 17560736

  • A study of image-guided intensity-modulated radiotherapy with fiducials for localized prostate cancer including pelvic lymph nodes INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Hsu, A., Pawlicki, T., Luxton, G., Hara, W., King, C. R. 2007; 68 (3): 898-902


    To study the impact on nodal coverage and dose to fixed organs at risk when using daily fiducial localization of the prostate to deliver intensity-modulated radiotherapy (IMRT).Five patients with prostate cancer in whom prostate and pelvic nodes were irradiated with IMRT were studied. Dose was prescribed such that 95% of the prostate planning target volume (PTV) and 90% of the nodal PTV were covered. Random and systematic prostate displacements in the anterior-posterior, superior-inferior, and left-right directions were simulated to shift the original isocenter of the IMRT plan. The composite dose during the course of treatment was calculated.Compared with a static setup, simulating random shifts reduced dose by less than 1.5% for nodal hotspot (i.e., dose to 1 cm(3)), by less than 1% for the 90% nodal PTV coverage, and by less than 0.5% for the nodal mean dose. Bowel and femoral head hotspots were reduced by less than 1.5% and 2%, respectively. A 10-mm systematic offset reduced nodal coverage by up to 10%.The use of prostate fiducials for daily localization during IMRT treatment results in negligible changes in dose coverage of pelvic nodes or normal tissue sparing in the absence of a significant systematic offset. This offers a simple and practical solution to the problem of image-guided radiotherapy for prostate cancer when including pelvic nodes.

    View details for DOI 10.1016/j.ijrobp.2007.02.030

    View details for Web of Science ID 000247284600035

    View details for PubMedID 17459610