- Email: [email protected]
Robotic Radiosurgery Boost for Cervical Cancer: A Dosimetric Study
Poster Viewing Abstracts S415
Volume 87 Number 2S Supplement 2013
2551 TCP-Driven Biological Planning for High-Dose-Rate Brachytherapy E.K. Lee,1 F. Yuan,1 A. Templeton,2 R. Yao,2 K. Kiel,2 and J. Chu2; 1 Georgia Institute of Technology, Atlanta, GA, 2Rush University, Chicago, IL Purpose/Objective(s): Tumor control probability (TCP) measures the probability that no malignant cells are left in the affected organ. It is thus an important clinical metric for measuring treatment success. Zaider and Minerbo provide a complex yet important TCP formalism which links the treatment duration, dose deposit, radiobiology of tumor cells and cell life characteristics. We perform feasibility tests on TCP-driven biological planning for high dose rate brachytherapy (HDR) where the objective maximizes TCP of the resulting plans. Robustness of the planning is tested, and plan quality and potential outcome significance are evaluated. Materials/Methods: CT and 18F-fluorodeoxyglucose based-PET images are obtained for 15 cervical cancer patients. All received prior external beam radiation. The CTV prescribed dose is 5 Gy for 4 fractionations, with the PET-identified pockets prescribed an escalated dose ranging from 7.59.0 Gy per fraction. The treatment model determines the dwell time and seed location that maximizes TCP while constraining PTV coverage, the lower/upper dose, and dose-volume shape for organs-at-risk and PTV. Two alternative plans are contrasted: standard HDR plan and PET-pocket escalated plan. Results: TCP for standard plans ranges from 48-63% whereas TCP for PET-guided escalated plans ranges from 82-99%. The increase is most significant with the smallest PET-identified pockets. Uniformly, bladder and rectum receive 5-8% reduced dose. There is a marginal difference in PTV dose between the standard and escalated plans. All resulting TCPdriven plans are clinically acceptable. Conclusions: TCP can be a very important objective for treatment plan optimization. With advances in biological/functional imaging, there is an urgent need to incorporate radiobiological parameters and TCP within the planning process. This study marks the first use of TCP as the driving objective for treatment planning. Although the optimization problem is very difficult to solve and requires computational breakthroughs, the resulting plans improve significantly the overall local tumor control, and also reduce dose to organs at risk. Rush University began clinical studies in July 2011. A long term outcome study must be carried out to gauge the overall impact. Author Disclosure: E.K. Lee: None. F. Yuan: None. A. Templeton: None. R. Yao: None. K. Kiel: None. J. Chu: None.
2552 Robotic Radiosurgery Boost for Cervical Cancer: A Dosimetric Study N. El-Bared, D. Be´liveau-Nadeau, J. Carrier, T. Nguyen, M. Beauchemin, and M. Barkati; CHUM, Montreal, QC, Canada Purpose/Objective(s): External beam radiation therapy (EBRT) combined with intracavitary high-dose rate (HDR) brachytherapy given with concomitant chemotherapy is the standard treatment for locally advanced cervical cancer. However, intracavitary brachytherapy is not always feasible. Our aim in this dosimetric study was to compare dosimetric parameters of HDR and robotic radiosurgery plans for boosts in cervical cancer patients. Materials/Methods: CT-based HDR plans of 14 patients with FIGO IB-IIIB cervical cancer treated in a single center were analyzed. Each patient was treated with weekly cisplatinum concomitantly with EBRT followed with HDR boost of 30 Gy in 5 fractions. Plans were generated using a radiation therapy treatment planning system and delivered with a digital afterloader platform. For each patient, 5 robotic radiosurgery plans were generated by an experienced physicist, using a treatment planning system for Robotic Radiosurgery system. For both modalities, treatment plans were generated using critical organs’ dose constraints recommended by GEC-ESTRO. Paired T tests were used to compare bladder, sigmoid, rectum and bowel D0.1 cc, D1 cc, D2 cc and D5 cc. Target volume dosimetric parameters as well as total tissue volume parameters were also compared.
Results: We are presenting preliminary results comparing 30 plans (6 patients) in each modality. Target volume (% of volume) D100 and D90 were significantly better for the robotic radiosurgery plans (p < 0.00). Total tissue volume (% of prescribed dose) V200 and V150 were significantly higher in HDR plans. Doses to all critical organs were higher for robotic radiosurgery plans. However, they were significantly higher only for bladder D5 cc (p < 0,000) and D0.1 cc (p Z 0.002), sigmoid D5 cc (p < 0.000) and D2 cc (p Z 0.015) and small bowel D5 cc (p < 0.000), D2 cc (p Z 0.001) and D1 cc (p Z 0.022). Low dose parameters for total tissue volume such as V50, V40, V30, V20 and V10 were all significantly higher in robotic radiosurgery plans (p < 0.000). Conclusions: Robotic radiosurgery plans had better target volume coverage and less dose heterogeneity, while HDR plans demonstrated lower doses to critical organs and consistently lower volume of total tissue receiving low doses. Based on this preliminary dosimetric study, boosting cervical cancer patients using robotic radiosurgery could be an alternative in patients that are not eligible for intracavitary HDR brachytherapy. However, further clinical research is needed before this treatment modality can be implemented. Author Disclosure: N. El-Bared: None. D. Be´liveau-Nadeau: None. J. Carrier: None. T. Nguyen: None. M. Beauchemin: None. M. Barkati: None.
2553 African-American Race and Low-Income Neighborhoods Decreased Cause-Specific Survival of Endometrial Cancer: A SEER Analysis M. Cheung; Independent contractor, Bryn Mawr, PA Purpose/Objective(s): This study analyzed Surveillance, Epidemiology and End Results (SEER) data to assess if socio-economic factors (SEFs) impact endometrial cancer survival. Materials/Methods: Endometrial cancer patients treated from 2004 to 2007 were included in this study. SEER cause specific survival (CSS) data were used as end points. The areas under the receiver operating characteristic (ROC) curve were computed for predictors. Time to event data was analyzed with Kaplan-Meier method. Univariate and multivariate analyses were used to identify independent risk factors. Results: This study included 64,710 patients. The mean follow-up time (S.D.) was 28.2 (20.8) months. SEER staging (ROC area of 0.81) was the best pretreatment predictor of CSS. Histology, grade, race/ethnicity and county level family income were also significant pretreatment predictors. African American race and low income neighborhoods decreased the CSS by 12% and 2%, respectively. Conclusions: This study has found significant endometrial survival disparities due to SEFs. Future studies should focus on eliminating socioeconomic barriers to good outcomes. Author Disclosure: M. Cheung: None.
2554 Administration of Concurrent Vaginal Brachytherapy During Chemotherapy for Treatment of Endometrial Cancer H. Nagar, D. Boothe, M. Yondorf, B. Parashar, D. Gupta, K. Holcomb, T. Caputo, K. Chao, D. Nori, and A. Wernicke; NYP-Cornell, New York, NY Purpose/Objective(s): Evaluate feasibility of administering vaginal brachytherapy (VB) during chemotherapy for patients with endometrial cancer. Materials/Methods: A retrospective analysis of 602 surgically staged patients with endometrial cancer AJCC 2009 Stages IA Grade 3-IVA treated with adjuvant postoperative radiation therapy (RT) at Weill Cornell Medical Center from 2001-2012 was conducted. All patients received VB external beam radiation therapy (EBRT). Among the 602 patients treated with RT, 423 (70%) patients received 6 cycles of adjuvant carboplatin and paclitaxel based chemotherapy. VB mean dose was 17.27 Gy (range, 15-21 Gy) with 3-4 weekly applications and EBRT mean dose was 45 Gy delivered with 3D or IMRT techniques. RTOG gastrointestinal (GI)
Volume 87 Number 2S Supplement 2013
2551 TCP-Driven Biological Planning for High-Dose-Rate Brachytherapy E.K. Lee,1 F. Yuan,1 A. Templeton,2 R. Yao,2 K. Kiel,2 and J. Chu2; 1 Georgia Institute of Technology, Atlanta, GA, 2Rush University, Chicago, IL Purpose/Objective(s): Tumor control probability (TCP) measures the probability that no malignant cells are left in the affected organ. It is thus an important clinical metric for measuring treatment success. Zaider and Minerbo provide a complex yet important TCP formalism which links the treatment duration, dose deposit, radiobiology of tumor cells and cell life characteristics. We perform feasibility tests on TCP-driven biological planning for high dose rate brachytherapy (HDR) where the objective maximizes TCP of the resulting plans. Robustness of the planning is tested, and plan quality and potential outcome significance are evaluated. Materials/Methods: CT and 18F-fluorodeoxyglucose based-PET images are obtained for 15 cervical cancer patients. All received prior external beam radiation. The CTV prescribed dose is 5 Gy for 4 fractionations, with the PET-identified pockets prescribed an escalated dose ranging from 7.59.0 Gy per fraction. The treatment model determines the dwell time and seed location that maximizes TCP while constraining PTV coverage, the lower/upper dose, and dose-volume shape for organs-at-risk and PTV. Two alternative plans are contrasted: standard HDR plan and PET-pocket escalated plan. Results: TCP for standard plans ranges from 48-63% whereas TCP for PET-guided escalated plans ranges from 82-99%. The increase is most significant with the smallest PET-identified pockets. Uniformly, bladder and rectum receive 5-8% reduced dose. There is a marginal difference in PTV dose between the standard and escalated plans. All resulting TCPdriven plans are clinically acceptable. Conclusions: TCP can be a very important objective for treatment plan optimization. With advances in biological/functional imaging, there is an urgent need to incorporate radiobiological parameters and TCP within the planning process. This study marks the first use of TCP as the driving objective for treatment planning. Although the optimization problem is very difficult to solve and requires computational breakthroughs, the resulting plans improve significantly the overall local tumor control, and also reduce dose to organs at risk. Rush University began clinical studies in July 2011. A long term outcome study must be carried out to gauge the overall impact. Author Disclosure: E.K. Lee: None. F. Yuan: None. A. Templeton: None. R. Yao: None. K. Kiel: None. J. Chu: None.
2552 Robotic Radiosurgery Boost for Cervical Cancer: A Dosimetric Study N. El-Bared, D. Be´liveau-Nadeau, J. Carrier, T. Nguyen, M. Beauchemin, and M. Barkati; CHUM, Montreal, QC, Canada Purpose/Objective(s): External beam radiation therapy (EBRT) combined with intracavitary high-dose rate (HDR) brachytherapy given with concomitant chemotherapy is the standard treatment for locally advanced cervical cancer. However, intracavitary brachytherapy is not always feasible. Our aim in this dosimetric study was to compare dosimetric parameters of HDR and robotic radiosurgery plans for boosts in cervical cancer patients. Materials/Methods: CT-based HDR plans of 14 patients with FIGO IB-IIIB cervical cancer treated in a single center were analyzed. Each patient was treated with weekly cisplatinum concomitantly with EBRT followed with HDR boost of 30 Gy in 5 fractions. Plans were generated using a radiation therapy treatment planning system and delivered with a digital afterloader platform. For each patient, 5 robotic radiosurgery plans were generated by an experienced physicist, using a treatment planning system for Robotic Radiosurgery system. For both modalities, treatment plans were generated using critical organs’ dose constraints recommended by GEC-ESTRO. Paired T tests were used to compare bladder, sigmoid, rectum and bowel D0.1 cc, D1 cc, D2 cc and D5 cc. Target volume dosimetric parameters as well as total tissue volume parameters were also compared.
Results: We are presenting preliminary results comparing 30 plans (6 patients) in each modality. Target volume (% of volume) D100 and D90 were significantly better for the robotic radiosurgery plans (p < 0.00). Total tissue volume (% of prescribed dose) V200 and V150 were significantly higher in HDR plans. Doses to all critical organs were higher for robotic radiosurgery plans. However, they were significantly higher only for bladder D5 cc (p < 0,000) and D0.1 cc (p Z 0.002), sigmoid D5 cc (p < 0.000) and D2 cc (p Z 0.015) and small bowel D5 cc (p < 0.000), D2 cc (p Z 0.001) and D1 cc (p Z 0.022). Low dose parameters for total tissue volume such as V50, V40, V30, V20 and V10 were all significantly higher in robotic radiosurgery plans (p < 0.000). Conclusions: Robotic radiosurgery plans had better target volume coverage and less dose heterogeneity, while HDR plans demonstrated lower doses to critical organs and consistently lower volume of total tissue receiving low doses. Based on this preliminary dosimetric study, boosting cervical cancer patients using robotic radiosurgery could be an alternative in patients that are not eligible for intracavitary HDR brachytherapy. However, further clinical research is needed before this treatment modality can be implemented. Author Disclosure: N. El-Bared: None. D. Be´liveau-Nadeau: None. J. Carrier: None. T. Nguyen: None. M. Beauchemin: None. M. Barkati: None.
2553 African-American Race and Low-Income Neighborhoods Decreased Cause-Specific Survival of Endometrial Cancer: A SEER Analysis M. Cheung; Independent contractor, Bryn Mawr, PA Purpose/Objective(s): This study analyzed Surveillance, Epidemiology and End Results (SEER) data to assess if socio-economic factors (SEFs) impact endometrial cancer survival. Materials/Methods: Endometrial cancer patients treated from 2004 to 2007 were included in this study. SEER cause specific survival (CSS) data were used as end points. The areas under the receiver operating characteristic (ROC) curve were computed for predictors. Time to event data was analyzed with Kaplan-Meier method. Univariate and multivariate analyses were used to identify independent risk factors. Results: This study included 64,710 patients. The mean follow-up time (S.D.) was 28.2 (20.8) months. SEER staging (ROC area of 0.81) was the best pretreatment predictor of CSS. Histology, grade, race/ethnicity and county level family income were also significant pretreatment predictors. African American race and low income neighborhoods decreased the CSS by 12% and 2%, respectively. Conclusions: This study has found significant endometrial survival disparities due to SEFs. Future studies should focus on eliminating socioeconomic barriers to good outcomes. Author Disclosure: M. Cheung: None.
2554 Administration of Concurrent Vaginal Brachytherapy During Chemotherapy for Treatment of Endometrial Cancer H. Nagar, D. Boothe, M. Yondorf, B. Parashar, D. Gupta, K. Holcomb, T. Caputo, K. Chao, D. Nori, and A. Wernicke; NYP-Cornell, New York, NY Purpose/Objective(s): Evaluate feasibility of administering vaginal brachytherapy (VB) during chemotherapy for patients with endometrial cancer. Materials/Methods: A retrospective analysis of 602 surgically staged patients with endometrial cancer AJCC 2009 Stages IA Grade 3-IVA treated with adjuvant postoperative radiation therapy (RT) at Weill Cornell Medical Center from 2001-2012 was conducted. All patients received VB external beam radiation therapy (EBRT). Among the 602 patients treated with RT, 423 (70%) patients received 6 cycles of adjuvant carboplatin and paclitaxel based chemotherapy. VB mean dose was 17.27 Gy (range, 15-21 Gy) with 3-4 weekly applications and EBRT mean dose was 45 Gy delivered with 3D or IMRT techniques. RTOG gastrointestinal (GI)