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Papers by Leonard Chen

Acta Oncologica, 2015

Acta Oncologica, 2015; Early online: 1-7 iSSN 0284-186X print/iSSN 1651-226X online © 2015 inform... more Acta Oncologica, 2015; Early online: 1-7 iSSN 0284-186X print/iSSN 1651-226X online © 2015 informa Healthcare

Radiation oncology (London, England), 2014

Urinary incontinence (UI) following prostate radiotherapy is a rare toxicity that adversely affec... more Urinary incontinence (UI) following prostate radiotherapy is a rare toxicity that adversely affects a patient's quality of life. This study sought to evaluate the incidence of UI following stereotactic body radiation therapy (SBRT) for prostate cancer. Between February, 2008 and October, 2010, 204 men with clinically localized prostate cancer were treated definitively with SBRT at Georgetown University Hospital. Patients were treated to 35-36.25 Gray (Gy) in 5 fractions delivered with the CyberKnife (Accuray). UI was assessed via the Expanded Prostate Index Composite (EPIC)-26. Baseline UI was common with 4.4%, 1.0% and 3.4% of patients reporting leaking > 1 time per day, frequent dribbling and pad usage, respectively. Three year post treatment, 5.7%, 6.4% and 10.8% of patients reported UI based on leaking > 1 time per day, frequent dribbling and pad usage, respectively. Average EPIC UI summary scores showed an acute transient decline at one month post-SBRT then a second a...

Journal of clinical oncology : official journal of the American Society of Clinical Oncology, Jan 20, 2014

Radiation Oncology, 2015

Hematuria following prostate radiotherapy is a known toxicity that may adversely affect a patient... more Hematuria following prostate radiotherapy is a known toxicity that may adversely affect a patient's quality of life. Given the higher dose of radiation per fraction using stereotactic body radiation therapy (SBRT) there is concern that post-SBRT hematuria would be more common than with alternative radiation therapy approaches. Herein, we describe the incidence and severity of hematuria following stereotactic body radiation therapy (SBRT) for prostate cancer at our institution. Two hundred and eight consecutive patients with prostate cancer treated with SBRT monotherapy with at least three years of follow-up were included in this retrospective analysis. Treatment was delivered using the CyberKnife® (Accuray) to doses of 35-36.25 Gy in 5 fractions. Toxicities were scored using the CTCAE v.4. Hematuria was counted at the highest grade it occurred in the acute and late setting for each patient. Cystoscopy findings were retrospectively reviewed. Univariate and multivariate analyses were performed. Hematuria-associated bother was assessed via the Expanded Prostate Index Composite (EPIC)-26. The median age was 69 years with a median prostate volume of 39 cc. With a median follow-up of 48 months, 38 patients (18.3%) experienced at least one episode of hematuria. Median time to hematuria was 13.5 months. In the late period, there were three grade 3 events and five grade 2 events. There were no grade 4 or 5 events. The 3-year actuarial incidence of late hematuria ≥ grade 2 was 2.4%. On univariate analysis, prostate volume (p = 0.022) and history of prior procedure(s) for benign prostatic hypertrophy (BPH) (p = 0.002) were significantly associated with hematuria. On multivariate analysis, history of prior procedure(s) for BPH (p < 0.0001) and α1A antagonist use (p = 0.008) were significantly associated with the development of hematuria. SBRT for prostate cancer was well tolerated with hematuria rates comparable to other radiation modalities. Patients factors associated with BPH, such as larger prostate volume, alpha antagonist usage, and prior history of procedures for BPH are at increased risk for the development of hematuria.

Acta Oncologica, 2014

Background. Stereotactic body radiotherapy (SBRT) has emerged as an effective treatment for local... more Background. Stereotactic body radiotherapy (SBRT) has emerged as an effective treatment for localized prostate cancer. However, prostate specific antigen (PSA) kinetics after prostate SBRT have not been well characterized. The purpose of this study was to analyze the trend in PSA decline following robotic SBRT from a prospective cohort of patients. Material and methods. In total 175 patients were treated definitively for localized prostate cancer to a dose of 35-36.25 Gy in 5 fractions using robotic SBRT in the absence of androgen deprivation therapy (ADT). PSA and testosterone were collected at regular intervals following treatment and patients were assessed for biochemical failure and benign PSA bounce. A PSA nadir threshold of 0.5 ng/ml was used as a predictor of long-term disease-free survival. Multivariate logistic regression was used to assess the effect of disease specific covariates on the likelihood of achieving a PSA nadir less than threshold. PSA kinetics were analyzed a multi-component exponential model accounting for benign and malignant sources of PSA. Results and conclusion. At a median follow-up of 3 years, 70% of patients achieved a PSA nadir below 0.5 ng/ml with a median PSA nadir of 0.3 ng/ml at a median time to nadir of 30 months. In our cohort, 36.2% experienced a benign PSA bounce. Absence of PSA bounce, initial PSA, and testosterone at the time of nadir proved to be significant predictors of achieving a PSA nadir below threshold. PSA kinetics after prostate SBRT were well described with a functional volume model with fitted half-lives of 4.4 and 14.8 months for malignant and benign sources of PSA, respectively. Patients treated with prostate SBRT experience an initial period of rapid PSA decline followed by a slow decline which will likely result in lower PSA nadirs after longer follow-up. The long-term disease specific impacts of these results remain to be determined.

Frontiers in Oncology, 2013

Benign tumors that arise from the meninges can be difficult to treat due to their potentially lar... more Benign tumors that arise from the meninges can be difficult to treat due to their potentially large size and proximity to critical structures such as cranial nerves and sinuses. Single fraction radiosurgery may increase the risk of symptomatic peritumoral edema. In this study, we report our results on the efficacy and safety of five fraction image-guided radiosurgery for benign meningiomas. Clinical and radiographic data from 38 patients treated with five fraction radiosurgery were reviewed retrospectively. Mean tumor volume was 3.83 mm(3) (range, 1.08-20.79 mm(3)). Radiation was delivered using the CyberKnife, a frameless robotic image-guided radiosurgery system with a median total dose of 25 Gy (range, 25-35 Gy). The median follow-up was 20 months. Acute toxicity was minimal with eight patients (21%) requiring a short course of steroids for headache at the end of treatment. Pre-treatment neurological symptoms were present in 24 patients (63.2%). Post treatment, neurological symptoms resolved completely in 14 patients (58.3%), and were persistent in eight patients (33.3%). There were no local failures, 24 tumors remained stable (64%) and 14 regressed (36%). Pre-treatment peritumoral edema was observed in five patients (13.2%). Post-treatment asymptomatic peritumoral edema developed in five additional patients (13.2%). On multivariate analysis, pre-treatment peritumoral edema and location adjacent to a large vein were significant risk factors for radiographic post-treatment edema (p = 0.001 and p = 0.026 respectively). These results suggest that five fraction image-guided radiosurgery is well tolerated with a response rate for neurologic symptoms that is similar to other standard treatment options. Rates of peritumoral edema and new cranial nerve deficits following five fraction radiosurgery were low. Longer follow-up is required to validate the safety and long-term effectiveness of this treatment approach.

Frontiers in oncology, 2014

Stereotactic body radiation therapy (SBRT) is increasingly utilized as primary treatment for clin... more Stereotactic body radiation therapy (SBRT) is increasingly utilized as primary treatment for clinically localized prostate cancer. While acute post-SBRT urinary symptoms are well recognized, the late genitourinary toxicity of SBRT has not been fully described. Here, we characterize the clinical features of late urinary symptom flare and recommend conservative symptom management approaches that may alleviate the associated bother. Between February 2008 and August 2011, 216 men with clinically localized prostate cancer were treated definitively with SBRT at Georgetown University Hospital. Treatment was delivered using the CyberKnife with doses of 35-36.25 Gy in five fractions. The prevalence of each of five Common Terminology Criteria for Adverse Events (CTCAE) graded urinary toxicities was assessed at each follow-up visit. Medication usage was documented at each visit. Patient-reported urinary symptoms were assessed using the American Urological Association (AUA) symptom score and th...

Frontiers in Oncology, 2013

Bhattasali et al. SBRT for oligometastatic prostate cancer

Radiation Oncology, 2014

Background: Stereotactic body radiation therapy (SBRT) delivers high doses of radiation to the pr... more Background: Stereotactic body radiation therapy (SBRT) delivers high doses of radiation to the prostate while minimizing radiation to adjacent normal tissues. Large fraction sizes may increase the risk of functional decrements. Treatment-related bother may be more important to a patient than treatment-related dysfunction. This study reports on patient-reported outcomes following SBRT for clinically localized prostate cancer.

PLoS ONE, 2013

Prostate cancer (PCa) is the most common type of cancer in men in the United States, which dispro... more Prostate cancer (PCa) is the most common type of cancer in men in the United States, which disproportionately affects African American descents. While metastasis is the most common cause of death among PCa patients, no specific markers have been assigned to severity and ethnic biasness of the disease. MicroRNAs represent a promising new class of biomarkers owing to their inherent stability and resilience. In the present study, we investigated potential miRNAs that can be used as biomarkers and/or therapeutic targets and can provide insight into the severity and ethnic biasness of PCa. PCR array was performed in FFPE PCa tissues (5 Caucasian American and 5 African American) and selected differentially expressed miRNAs were validated by qRT-PCR, in 40 (15 CA and 25 AA) paired PCa and adjacent normal tissues. Significantly deregulated miRNAs were also analyzed in urine samples to explore their potential as non-invasive biomarker for PCa. Out of 8 miRNAs selected for validation from PCR array data, miR-205 (p,0.0001), mir-214 (p,0.0001), miR-221(p,0.001) and miR-99b (p,0.0001) were significantly downregulated in PCa tissues. ROC curve shows that all four miRNAs successfully discriminated between PCa and adjacent normal tissues. MiR-99b showed significant down regulation (p,0.01) in AA PCa tissues as compared to CA PCa tissues and might be related to the aggressiveness associated with AA population. In urine, miR-205 (p,0.05) and miR-214 (p,0.05) were significantly downregulated in PCa patients and can discriminate PCa patients from healthy individuals with 89% sensitivity and 80% specificity. In conclusion, present study showed that miR-205 and miR-214 are downregulated in PCa and may serve as potential non-invasive molecular biomarker for PCa. Citation: Srivastava A, Goldberger H, Dimtchev A, Ramalinga M, Chijioke J, et al. (2013) MicroRNA Profiling in Prostate Cancer -The Diagnostic Potential of Urinary miR-205 and miR-214. PLoS ONE 8(10): e76994.

The Journal of Urology, 2013

International Journal of Radiation Oncology*Biology*Physics, 2012

International Journal of Radiation Oncology*Biology*Physics, 2011

ABSTRACT PURPOSE Radiation therapy has had a limited role in the treatment of many gastrointestin... more ABSTRACT PURPOSE Radiation therapy has had a limited role in the treatment of many gastrointestinal (GI) malignancies, including primary liver tumors and local or lymph node recurrences, due to the particular radiosensitivity of abdominal organs such as the small bowel and liver. Stereotactic body radiation therapy (SBRT) enables delivery of high doses of radiation to a tumor while limiting the dose received by critical surrounding organs. The purpose of this study was to evaluate the feasibility and efficacy of SBRT for primary and recurrent GI malignancies. METHOD AND MATERIALS Between February 2002 and February 2008, 46 lesions in 34 patients were treated with SBRT using a 6 MV linear accelerator (Novalis) and an infrared-based patient tracking system. The liver tumors included hepatocellular carcinoma (primary n = 7, recurrent n = 4) and cholangiocarcinoma (primary n = 3, recurrent n = 1). Additional sites treated were pancreas (n = 5), lymph nodes (n =10), and abdominopelvic recurrences (n = 4). SBRT was used as a boost treatment in 4 patients. The GTV size ranged from 1-11 cm (median 3.1cm). Median age was 67 years (range: 22-85 years). Dose per fraction ranged from 2.5-5Gy. A median total dose of 36 Gy (range: 8-50 Gy) was delivered in 2 to 16 fractions. Doses were prescribed to the 100% isodose line (IDL), with the 80% IDL covering the gross tumor volume plus a minimum margin of 7 mm. RESULTS The median follow-up was 7.7 months (range 0.2- 47.4 months). All patients completed treatment as prescribed. Thirty-one (91%) of the 34 patients were evaluable for response based on abdominal CT performed at a minimum of 2.5 months following completion of treatment. Response was evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines. The overall in-field local control rate was 77%. Complete response (CR) was seen in 5 patients, partial response (PR) in 6 patients, and stable disease (SD) in 13 patients. The mean and median survivals were 11.4 months and 7.7 months respectively. None of the patients developed grade 3 or higher toxicity. CONCLUSION In selected patients with primary or recurrent GI malignancies, SBRT provides excellent in-field control with minimal side effects

American Journal of Clinical Oncology, 2013

Cancer Treatment Reviews, 2013

Prostate cancer is the second most prevalent solid tumor diagnosed in men in the United States an... more Prostate cancer is the second most prevalent solid tumor diagnosed in men in the United States and Western Europe. Stereotactic body radiation therapy (SBRT) is touted as a superior type of external beam radiation therapy (EBRT) for the treatment of various tumors. SBRT developed from the theory that high doses of radiation from brachytherapy implant seeds could be recapitulated from advanced technology of radiation treatment planning and delivery. Moreover, SBRT has been theorized to be advantageous compared to other RT techniques because it has a treatment course shorter than that of conventionally fractionated EBRT (a single session, five days per week, for about two weeks vs. eight weeks), is non-invasive, is more effective at killing tumor cells, and is less likely to cause damage to normal tissue. In areas of the US and Europe where there is limited access to RT centers, SBRT is frequently being used to treat prostate cancer, even though long-term data about its efficacy and safety are not well established. We review the impetus behind SBRT and the current clinical evidence supporting its use for prostate cancer, thus providing oncologists and primary care physicians with an understanding of the continually evolving field of prostate radiation therapy. Studies of SBRT provide encouraging results of biochemical control and late toxicity. However, they are limited by a number of factors, including short follow-up, exclusion of intermediate-and high-risk patients, and relatively small number of patients treated. Currently, SBRT regimens should only be used in the context of clinical trials.

Acta Oncologica, 2015

Acta Oncologica, 2015; Early online: 1-7 iSSN 0284-186X print/iSSN 1651-226X online © 2015 inform... more Acta Oncologica, 2015; Early online: 1-7 iSSN 0284-186X print/iSSN 1651-226X online © 2015 informa Healthcare

Radiation oncology (London, England), 2014

Urinary incontinence (UI) following prostate radiotherapy is a rare toxicity that adversely affec... more Urinary incontinence (UI) following prostate radiotherapy is a rare toxicity that adversely affects a patient's quality of life. This study sought to evaluate the incidence of UI following stereotactic body radiation therapy (SBRT) for prostate cancer. Between February, 2008 and October, 2010, 204 men with clinically localized prostate cancer were treated definitively with SBRT at Georgetown University Hospital. Patients were treated to 35-36.25 Gray (Gy) in 5 fractions delivered with the CyberKnife (Accuray). UI was assessed via the Expanded Prostate Index Composite (EPIC)-26. Baseline UI was common with 4.4%, 1.0% and 3.4% of patients reporting leaking > 1 time per day, frequent dribbling and pad usage, respectively. Three year post treatment, 5.7%, 6.4% and 10.8% of patients reported UI based on leaking > 1 time per day, frequent dribbling and pad usage, respectively. Average EPIC UI summary scores showed an acute transient decline at one month post-SBRT then a second a...

Journal of clinical oncology : official journal of the American Society of Clinical Oncology, Jan 20, 2014

Radiation Oncology, 2015

Hematuria following prostate radiotherapy is a known toxicity that may adversely affect a patient... more Hematuria following prostate radiotherapy is a known toxicity that may adversely affect a patient's quality of life. Given the higher dose of radiation per fraction using stereotactic body radiation therapy (SBRT) there is concern that post-SBRT hematuria would be more common than with alternative radiation therapy approaches. Herein, we describe the incidence and severity of hematuria following stereotactic body radiation therapy (SBRT) for prostate cancer at our institution. Two hundred and eight consecutive patients with prostate cancer treated with SBRT monotherapy with at least three years of follow-up were included in this retrospective analysis. Treatment was delivered using the CyberKnife® (Accuray) to doses of 35-36.25 Gy in 5 fractions. Toxicities were scored using the CTCAE v.4. Hematuria was counted at the highest grade it occurred in the acute and late setting for each patient. Cystoscopy findings were retrospectively reviewed. Univariate and multivariate analyses were performed. Hematuria-associated bother was assessed via the Expanded Prostate Index Composite (EPIC)-26. The median age was 69 years with a median prostate volume of 39 cc. With a median follow-up of 48 months, 38 patients (18.3%) experienced at least one episode of hematuria. Median time to hematuria was 13.5 months. In the late period, there were three grade 3 events and five grade 2 events. There were no grade 4 or 5 events. The 3-year actuarial incidence of late hematuria ≥ grade 2 was 2.4%. On univariate analysis, prostate volume (p = 0.022) and history of prior procedure(s) for benign prostatic hypertrophy (BPH) (p = 0.002) were significantly associated with hematuria. On multivariate analysis, history of prior procedure(s) for BPH (p < 0.0001) and α1A antagonist use (p = 0.008) were significantly associated with the development of hematuria. SBRT for prostate cancer was well tolerated with hematuria rates comparable to other radiation modalities. Patients factors associated with BPH, such as larger prostate volume, alpha antagonist usage, and prior history of procedures for BPH are at increased risk for the development of hematuria.

Acta Oncologica, 2014

Background. Stereotactic body radiotherapy (SBRT) has emerged as an effective treatment for local... more Background. Stereotactic body radiotherapy (SBRT) has emerged as an effective treatment for localized prostate cancer. However, prostate specific antigen (PSA) kinetics after prostate SBRT have not been well characterized. The purpose of this study was to analyze the trend in PSA decline following robotic SBRT from a prospective cohort of patients. Material and methods. In total 175 patients were treated definitively for localized prostate cancer to a dose of 35-36.25 Gy in 5 fractions using robotic SBRT in the absence of androgen deprivation therapy (ADT). PSA and testosterone were collected at regular intervals following treatment and patients were assessed for biochemical failure and benign PSA bounce. A PSA nadir threshold of 0.5 ng/ml was used as a predictor of long-term disease-free survival. Multivariate logistic regression was used to assess the effect of disease specific covariates on the likelihood of achieving a PSA nadir less than threshold. PSA kinetics were analyzed a multi-component exponential model accounting for benign and malignant sources of PSA. Results and conclusion. At a median follow-up of 3 years, 70% of patients achieved a PSA nadir below 0.5 ng/ml with a median PSA nadir of 0.3 ng/ml at a median time to nadir of 30 months. In our cohort, 36.2% experienced a benign PSA bounce. Absence of PSA bounce, initial PSA, and testosterone at the time of nadir proved to be significant predictors of achieving a PSA nadir below threshold. PSA kinetics after prostate SBRT were well described with a functional volume model with fitted half-lives of 4.4 and 14.8 months for malignant and benign sources of PSA, respectively. Patients treated with prostate SBRT experience an initial period of rapid PSA decline followed by a slow decline which will likely result in lower PSA nadirs after longer follow-up. The long-term disease specific impacts of these results remain to be determined.

Frontiers in Oncology, 2013

Benign tumors that arise from the meninges can be difficult to treat due to their potentially lar... more Benign tumors that arise from the meninges can be difficult to treat due to their potentially large size and proximity to critical structures such as cranial nerves and sinuses. Single fraction radiosurgery may increase the risk of symptomatic peritumoral edema. In this study, we report our results on the efficacy and safety of five fraction image-guided radiosurgery for benign meningiomas. Clinical and radiographic data from 38 patients treated with five fraction radiosurgery were reviewed retrospectively. Mean tumor volume was 3.83 mm(3) (range, 1.08-20.79 mm(3)). Radiation was delivered using the CyberKnife, a frameless robotic image-guided radiosurgery system with a median total dose of 25 Gy (range, 25-35 Gy). The median follow-up was 20 months. Acute toxicity was minimal with eight patients (21%) requiring a short course of steroids for headache at the end of treatment. Pre-treatment neurological symptoms were present in 24 patients (63.2%). Post treatment, neurological symptoms resolved completely in 14 patients (58.3%), and were persistent in eight patients (33.3%). There were no local failures, 24 tumors remained stable (64%) and 14 regressed (36%). Pre-treatment peritumoral edema was observed in five patients (13.2%). Post-treatment asymptomatic peritumoral edema developed in five additional patients (13.2%). On multivariate analysis, pre-treatment peritumoral edema and location adjacent to a large vein were significant risk factors for radiographic post-treatment edema (p = 0.001 and p = 0.026 respectively). These results suggest that five fraction image-guided radiosurgery is well tolerated with a response rate for neurologic symptoms that is similar to other standard treatment options. Rates of peritumoral edema and new cranial nerve deficits following five fraction radiosurgery were low. Longer follow-up is required to validate the safety and long-term effectiveness of this treatment approach.

Frontiers in oncology, 2014

Stereotactic body radiation therapy (SBRT) is increasingly utilized as primary treatment for clin... more Stereotactic body radiation therapy (SBRT) is increasingly utilized as primary treatment for clinically localized prostate cancer. While acute post-SBRT urinary symptoms are well recognized, the late genitourinary toxicity of SBRT has not been fully described. Here, we characterize the clinical features of late urinary symptom flare and recommend conservative symptom management approaches that may alleviate the associated bother. Between February 2008 and August 2011, 216 men with clinically localized prostate cancer were treated definitively with SBRT at Georgetown University Hospital. Treatment was delivered using the CyberKnife with doses of 35-36.25 Gy in five fractions. The prevalence of each of five Common Terminology Criteria for Adverse Events (CTCAE) graded urinary toxicities was assessed at each follow-up visit. Medication usage was documented at each visit. Patient-reported urinary symptoms were assessed using the American Urological Association (AUA) symptom score and th...

Frontiers in Oncology, 2013

Bhattasali et al. SBRT for oligometastatic prostate cancer

Radiation Oncology, 2014

Background: Stereotactic body radiation therapy (SBRT) delivers high doses of radiation to the pr... more Background: Stereotactic body radiation therapy (SBRT) delivers high doses of radiation to the prostate while minimizing radiation to adjacent normal tissues. Large fraction sizes may increase the risk of functional decrements. Treatment-related bother may be more important to a patient than treatment-related dysfunction. This study reports on patient-reported outcomes following SBRT for clinically localized prostate cancer.

PLoS ONE, 2013

Prostate cancer (PCa) is the most common type of cancer in men in the United States, which dispro... more Prostate cancer (PCa) is the most common type of cancer in men in the United States, which disproportionately affects African American descents. While metastasis is the most common cause of death among PCa patients, no specific markers have been assigned to severity and ethnic biasness of the disease. MicroRNAs represent a promising new class of biomarkers owing to their inherent stability and resilience. In the present study, we investigated potential miRNAs that can be used as biomarkers and/or therapeutic targets and can provide insight into the severity and ethnic biasness of PCa. PCR array was performed in FFPE PCa tissues (5 Caucasian American and 5 African American) and selected differentially expressed miRNAs were validated by qRT-PCR, in 40 (15 CA and 25 AA) paired PCa and adjacent normal tissues. Significantly deregulated miRNAs were also analyzed in urine samples to explore their potential as non-invasive biomarker for PCa. Out of 8 miRNAs selected for validation from PCR array data, miR-205 (p,0.0001), mir-214 (p,0.0001), miR-221(p,0.001) and miR-99b (p,0.0001) were significantly downregulated in PCa tissues. ROC curve shows that all four miRNAs successfully discriminated between PCa and adjacent normal tissues. MiR-99b showed significant down regulation (p,0.01) in AA PCa tissues as compared to CA PCa tissues and might be related to the aggressiveness associated with AA population. In urine, miR-205 (p,0.05) and miR-214 (p,0.05) were significantly downregulated in PCa patients and can discriminate PCa patients from healthy individuals with 89% sensitivity and 80% specificity. In conclusion, present study showed that miR-205 and miR-214 are downregulated in PCa and may serve as potential non-invasive molecular biomarker for PCa. Citation: Srivastava A, Goldberger H, Dimtchev A, Ramalinga M, Chijioke J, et al. (2013) MicroRNA Profiling in Prostate Cancer -The Diagnostic Potential of Urinary miR-205 and miR-214. PLoS ONE 8(10): e76994.

The Journal of Urology, 2013

International Journal of Radiation Oncology*Biology*Physics, 2012

International Journal of Radiation Oncology*Biology*Physics, 2011

ABSTRACT PURPOSE Radiation therapy has had a limited role in the treatment of many gastrointestin... more ABSTRACT PURPOSE Radiation therapy has had a limited role in the treatment of many gastrointestinal (GI) malignancies, including primary liver tumors and local or lymph node recurrences, due to the particular radiosensitivity of abdominal organs such as the small bowel and liver. Stereotactic body radiation therapy (SBRT) enables delivery of high doses of radiation to a tumor while limiting the dose received by critical surrounding organs. The purpose of this study was to evaluate the feasibility and efficacy of SBRT for primary and recurrent GI malignancies. METHOD AND MATERIALS Between February 2002 and February 2008, 46 lesions in 34 patients were treated with SBRT using a 6 MV linear accelerator (Novalis) and an infrared-based patient tracking system. The liver tumors included hepatocellular carcinoma (primary n = 7, recurrent n = 4) and cholangiocarcinoma (primary n = 3, recurrent n = 1). Additional sites treated were pancreas (n = 5), lymph nodes (n =10), and abdominopelvic recurrences (n = 4). SBRT was used as a boost treatment in 4 patients. The GTV size ranged from 1-11 cm (median 3.1cm). Median age was 67 years (range: 22-85 years). Dose per fraction ranged from 2.5-5Gy. A median total dose of 36 Gy (range: 8-50 Gy) was delivered in 2 to 16 fractions. Doses were prescribed to the 100% isodose line (IDL), with the 80% IDL covering the gross tumor volume plus a minimum margin of 7 mm. RESULTS The median follow-up was 7.7 months (range 0.2- 47.4 months). All patients completed treatment as prescribed. Thirty-one (91%) of the 34 patients were evaluable for response based on abdominal CT performed at a minimum of 2.5 months following completion of treatment. Response was evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines. The overall in-field local control rate was 77%. Complete response (CR) was seen in 5 patients, partial response (PR) in 6 patients, and stable disease (SD) in 13 patients. The mean and median survivals were 11.4 months and 7.7 months respectively. None of the patients developed grade 3 or higher toxicity. CONCLUSION In selected patients with primary or recurrent GI malignancies, SBRT provides excellent in-field control with minimal side effects

American Journal of Clinical Oncology, 2013

Cancer Treatment Reviews, 2013

Prostate cancer is the second most prevalent solid tumor diagnosed in men in the United States an... more Prostate cancer is the second most prevalent solid tumor diagnosed in men in the United States and Western Europe. Stereotactic body radiation therapy (SBRT) is touted as a superior type of external beam radiation therapy (EBRT) for the treatment of various tumors. SBRT developed from the theory that high doses of radiation from brachytherapy implant seeds could be recapitulated from advanced technology of radiation treatment planning and delivery. Moreover, SBRT has been theorized to be advantageous compared to other RT techniques because it has a treatment course shorter than that of conventionally fractionated EBRT (a single session, five days per week, for about two weeks vs. eight weeks), is non-invasive, is more effective at killing tumor cells, and is less likely to cause damage to normal tissue. In areas of the US and Europe where there is limited access to RT centers, SBRT is frequently being used to treat prostate cancer, even though long-term data about its efficacy and safety are not well established. We review the impetus behind SBRT and the current clinical evidence supporting its use for prostate cancer, thus providing oncologists and primary care physicians with an understanding of the continually evolving field of prostate radiation therapy. Studies of SBRT provide encouraging results of biochemical control and late toxicity. However, they are limited by a number of factors, including short follow-up, exclusion of intermediate-and high-risk patients, and relatively small number of patients treated. Currently, SBRT regimens should only be used in the context of clinical trials.