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A Comparative Dosimetric Feasibility Study of Robotic Radiosurgery, Volumetric Modulated Arc Therapy, and High Dose–Rate Brachytherapy in the Delivery of a Focal Integrated Boost for Low Risk Prostate Cancer
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International Journal of Radiation Oncology Biology Physics
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year. A recent survey of practicing radiation oncologists in the United States reports that almost half recommend adjuvant radiation therapy (RT) for locally advanced bladder cancer with over 90% of this group supporting the use of adjuvant RT for positive surgical margins. We sought to determine whether these physician treatment recommendations are reflected in national practice patterns. Materials/Methods: Using the National Cancer Database (NCDB), we identified patients diagnosed with non-metastatic urothelial cell or squamous cell bladder cancer from 2004 to 2014 who were treated with radical cystectomy. We studied patterns of care with regards to receipt of adjuvant RT in the overall cohort and in the positive surgical margin subgroup. Multivariable logistic regression was used to identify factors associated with receipt of adjuvant RT. Results: 46,380 patients met inclusion criteria for the overall cohort of which only 488 (1.1%) received adjuvant RT. In the overall cohort, receipt of adjuvant RT was significantly associated with squamous cell carcinoma histology (ORZ4.10, 95%CI 3.16-5.32; p<0.001), higher pathologic T stage (ORZ13.6, 95%CI 1.89-97.76; pZ0.01), and positive surgical margins (ORZ3.76, 95%CI 2.95-4.81; p<0.001). Other variables significantly associated with receipt of adjuvant RT included treatment at non-academic facilities, receipt of chemotherapy, and earlier year of diagnosis. Notably, age, race, comorbidity, and pathologic N stage did not impact receipt of adjuvant RT. There were 2,766 patients in the positive surgical margin subgroup of which only 120 (4.3%) patients received adjuvant RT. The utilization of adjuvant radiation in positive margin patients did not vary substantially over the study period. In 2004, 14/160 (8.8%) patients received adjuvant RT while 14/289 (4.8%) patients received adjuvant RT in 2014. On multivariable analysis, receipt of adjuvant RT was significantly associated with treatment at non-academic facilities, squamous cell carcinoma histology, receipt of chemotherapy, and an earlier year of diagnosis. Conclusion: In this patterns of care study, less than 5% of patients with positive surgical margins following radical cystectomy received adjuvant radiation therapy from 2004 to 2014. There appears to be a large discrepancy between the inclinations of practicing radiation oncologists and the actual practice patterns for this patient subgroup despite poor overall outcomes. These findings suggest that further work is needed to understand the risks and benefits of adjuvant RT, and may reflect a lack of multi-disciplinary care in the management of locally advanced bladder cancer. Author Disclosure: S. Venigalla: None. A.K. Chowdhry: None. D.M. Guttmann: None. B.C. Baumann: None. A. Cohen: None. R. Mamtani: None. J.P. Christodouleas: None.
100 Patients’ Experience with Brachytherapy in Bladder Implantations Performed Laparoscopically in Solitary Bladder Tumors E. van der Steen-Banasi,1 B. Oosterveld,1 C. Wijburg,2 T. Janssen,1 M. Haverkort,1 and G. Smits2; 1Radiotherapiegroep, location Arnhem, Arnhem, Netherlands, 2Rijnstate Hospital Arnhem, Arnhem, Netherlands Purpose/Objective(s): The results of the bladder sparing treatment including brachytherapy, using minimally invasive surgery to implant catheters are reported for the first 100 patients. The brachytherapy treatment was performed using initially PDR (NZ7), later with an HDR scheme. After the start in 2009 the laparoscopy technique was optimized by the use of daVinci robot platform and development of a dedicated Luneray catheter. Materials/Methods: The indication is a solitary tumor, pT1-3a, grade 2-3, no carcinoma in situ, tumor size 5 cm. After TURB and a course of external beam irradiation (40 Gy / 20 fractions, CTV including bladder and regional lymph nodes) brachytherapy follows within 10 days. A laparoscopic robot-assisted implantation procedure is performed, in selected cases combined with partial cystectomy (PC). A partial lymph node dissection (PLND) is performed if lymph node metastases are suspected on MRI. The HDR fractionation scheme was: 25 Gy in 10 fractions with 4 h interval, 3 fractions/day, prescribed at 5 mm from the catheters. An afterloader with an Ir-192 source with activity 37-13 GBq was used. Posttreatment cystoscopies and urine cytology were performed every 3 months. Results: The average tumor diameter was 2.5 cm. 31 patients underwent PC (NZ16 residual tumor), 28: PLND (resected lymph nodes nZ139 with 2 metastatic). 2-6 catheters were inserted, mean V100 was 12.5 cc. Organs at risk: bowel average D2ccZ8 Gy; D0.1ccZ15 Gy. Average hospitalization time: 6.4 days mainly due to irradiation time, is significantly reduced compared to the open procedure (15.4 days, NZ97). There was practically no blood loss or wound healing problems. Compared to the open procedure there was a significant reduction in catheter accessibility problems during irradiation. Implant quality parameters were comparable to the open procedure. 17 patients developed toxicity (CTCAE v 4): acute G3-5: delirium (NZ3), ileus (NZ1) pulmonary embolism (NZ1), fatal myocardial infarction (NZ1); late G2-3: hematuria (NZ3), urinary urgency (NZ3), lymphedema (NZ2), bladder necrosis (NZ1), recurrent cystitis (NZ1), hydronephrosis (NZ1). The average duration of the follow up was 2.0 y (range 1 m-7.0 y). Survival analysis was performed using the Kaplan e Meier method: 2-y local control was 80% and 2-y disease specific survival was 86%. Conclusion: Minimally invasive surgery improved patients’ post-operative recovery by reducing the amount of perioperative adverse events, shortening the hospitalization time and reducing treatment disturbances due to catheter accessibility. In addition, the patient’s well-being was improved by preventing isolated hospitalization. By using a robot platform during laparoscopy, tumor located in the previously inaccessible area of trigonum can be implanted. With the use of the HDR schedule we achieved satisfactory results with mild toxicity. Author Disclosure: E. van der Steen-Banasi: None. B. Oosterveld: None. C. Wijburg: None. T. Janssen: None. M. Haverkort: None. G. Smits: None.
2645 Adjuvant Radiation Therapy for Positive Surgical Margins Following Radical Cystectomy for Bladder Cancer: A National Patterns of Care Assessment S. Venigalla,1 A.K. Chowdhry,2 D.M. Guttmann,1 B.C. Baumann,3 A. Cohen,4 R. Mamtani,4 and J.P. Christodouleas3; 1Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 2 University of Rochester School of Medicine, Rochester, NY, 3University of Pennsylvania, Department of Radiation Oncology, Philadelphia, PA, 4 University of Pennsylvania, Department of Medical Oncology, Philadelphia, PA Purpose/Objective(s): Bladder cancer patients with a positive surgical margin after radical cystectomy have a median recurrence free survival of less than one
2646 A Comparative Dosimetric Feasibility Study of Robotic Radiosurgery, Volumetric Modulated Arc Therapy, and High DoseeRate Brachytherapy in the Delivery of a Focal Integrated Boost for Low Risk Prostate Cancer D.D. Vignarajah, Y.M. Tsang, P. Nariyangadu, H. Tharmalingam, G. Lowe, R. Alonzi, and P. Hoskin; Mount Vernon Cancer Centre, London, United Kingdom Purpose/Objective(s): Dose escalation to a dominant lesion with adjacent prostate sparing is a new approach to radical radiotherapy in early stage prostate cancer. We have used a focal integrated boost using high dose rate (HDR) brachytherapy and in this study ascertain whether HDR dosimetry can be achieved with robotic radiosurgery (RS) and volumetric modulated arc therapy (VMAT). Materials/Methods: Twelve patients who required histologically confirmed isolated disease correlating with a solitary focus on multiparametric MRI were included. Volumes were defined on planning CT and MRI. CTV1 was the prostate +/- base of seminal vesicles. CTV2 was the dominant lesion seen on multiparametric MRI. An additional 3mm margin, isotropic but avoiding rectum, was added to form PTV1 and 2 respectively. A single dose of 15Gy was prescribed to PTV1 and 21Gy to PTV2 as per the trial protocol. RS and VMAT plans were optimized using brachytherapy constraints. Planning objectives were V100>95% for PTVs 1 and 2. Urethral constraints were D10%<20.8Gy, D30%<22Gy and V28.5Gy Z 0. Rectal constraints were
Volume 99 Number 2S Supplement 2017
Poster Viewing E271
Abstract 2646 Planning parameters D10% Urethra D30% Urethra D2cc Rectum V150% PTV2 V200% PTV2 V19Gy PTV1 Conformity Index PTV boost Gradient Index (R50%)
Brachytherapy Mean (95%CI)
RS Mean (95%CI)
VMAT Mean (95%CI)
19.2Gy (18.1-20.3) 18.3Gy (17.3-19.2) 10.4Gy (9.7-11.1) 36.4% (31.9-40.9) 9.9% (6.1-13.7) 59.0% (52.9-65.2) 4.30 (3.03-5.56)
18.2Gy (17.5-18.9) 17.7Gy (17.0-18.4) 11.6Gy (11.0-12.3) 0 0 41.3% (33.4-49.3) 1.98 (1.53-2.43)
17.6Gy (16.5-18.6) 16.5Gy (15.9-17.1) 10.6Gy (10.2-10.9) 0 0 9.0% (7.4-10.6) 1.08 (1.07-1.09)
2.87 (2.75-3.00)
4.01 (3.77-4.24)
3.88 (3.75-4.02)
D2cc <15Gy and V19Gy Z 0cc. For each planning objective, Kruskal-Wallis ANOVA was performed to detect any significant difference between the three techniques, followed by the Bonferroni-type multiple comparison. Results: The mean PTV2 volume was 11.2cc (95%CI 7.5-14.9); PTV1 62.2cc (95%CI 50.4-74.0); mean rectal volume 33.6cc (95%CI 50.4-74.0); and mean urethral volume 2.0cc (95%CI 1.7-2.2). All techniques achieved the planning objectives, except for one brachytherapy plan which failed to achieve the V100>95% PTV1 objective. Organ at risk constraints were met in all 3 techniques. RS and VMAT plans managed to achieve lower urethral doses compared to brachytherapy although RS had the highest rectal D2cc. The conformity index was significantly better using the VMAT and RS compared to brachytherapy (p<0.05). The latter however had a superior gradient index (p<0.05). Brachytherapy delivered significant areas of high dose reflected in the V150%, V200% and equivalent uniform dose, which were unattainable with RS and VMAT. The V19Gy for the remainder of the gland, reflecting prostate sparing, was consequently higher. Conclusion: It is feasible to deliver an integrated focal boost in prostate monotherapy with HDR brachytherapy, RS and VMAT. Brachytherapy achieves significantly higher intraprostatic doses at the expense of decreased normal prostate sparing. Author Disclosure: D.D. Vignarajah: None. Y. Tsang: None. P. Nariyangadu: None. H. Tharmalingam: None. G. Lowe: None. R. Alonzi: None. P. Hoskin: Travel Expenses; Ain Shams University, American College of Radiology, Australian Brachytherapy group, ECCO, ESTRO. COUNCIL; Royal College of Radiologists. Advisory committees; NICE; ESTRO, Radiotherapy and Oncology.
2647 The Risk of Second Malignancies after Seed Migration in Prostate Cancer Patients Treated With I-125 Free Seeds Brachytherapy E. Vigneault,1,2 K. Martell,3 D. Taussky,4 S.M. Husain,5 G. Delouya,4 K. Mbodji,1 S. Magnan,6 P. Despres,2,6 M.C. Lavallee,2 S. Aubin,2 L. Beaulieu,2,6 W. Foster,2 and A.G. Martin1,2; 1Cancer Research Centre, University of Laval, Quebec, QC, Canada, 2Radiation Oncology, CHU de Quebec, Quebec, QC, Canada, 3University of Calgary, Calgary, AB, Canada, 4Universite de Montreal, Montreal, QC, Canada, 5Tom Baker Cancer Centre, Calgary, AB, Canada, 6University of Laval, Quebec, QC, Canada Purpose/Objective(s): To evaluate the risk of second malignancies after seed migration in prostate cancer patients treated with I-125 free seeds brachytherapy. Materials/Methods: Data from 2067 prostate cancer patients treated with I-125 free seeds brachytherapy in three Canadian centers were analyzed. Kaplan-Meier method was used to estimate the 5- and 7-year biochemical relapse-free and overall survival between patients who experienced or not seed migration. Results: Mean age and Median follow-up was 64 years and 44 (range 1147) months, respectively. Seed migration occurred in 365 of 2067 patients (17.7%). The 5-, 7-year biochemical relapse-free and overall survival for the entire cohort was 96%, 91.7% and 95.9%, 93.7%, respectively. Second malignancies occurred in 4 of 365 patients (1.1%) and 21 of 1702 patients (1.2%) in patients with or without seed migration, respectively (pZ0.827).
Lung cancer represented the most frequent second malignancy observed and occurred in 6 patients, all in the no seed migration group. The other second malignancies observed in the no seed migration group included: larynx (3 patients), colon (2 patients), esophagus (2), pancreatic (2), renal, myeloma, glioblastoma, non-Hodgkin’s lymphoma (1) and 2 unknown. In the seed migration group, the second malignancies observed were chronic myeloid leukemia (1), colo-rectal cancer (2) and nasopharynx (1). Conclusion: These short-term results do not support an increased risk of second malignancies, particularly lung cancer with seed migration after I-125 free seeds brachytherapy for prostate cancer patients. Due to the low rate of second malignancies observed in this cohort, further studies with longer follow-up are required to better correlate seed migration and second malignancies. Author Disclosure: E. Vigneault: Independent Contractor; CHUQ L’Hotel Dieu de Que´bec. Honoraria; Abbvie. Advisory Board; Abbvie. K. Martell: None. D. Taussky: None. S.M. Husain: None. G. Delouya: Partner; YAD Technologies. Research Grant; Janssen, Astellas, Ferring, Bayer. Honoraria; Janssen, Astellas, Ferring, Bayer. Advisory Board; Janssen, Astellas, Ferring, Bayer. Travel Expenses; Janssen, Astellas, Ferring, Bayer; CARO. K. Mbodji: None. S. Magnan: None. P. Despres: None. M. Lavallee: None. S. Aubin: None. L. Beaulieu: Research Grant; Elekta, Philips Medical. Royalty; Standard Imaging Inc. Patent/License Fees/Copyright; Standard Imaging Inc. Officer and Board Member; Canadian Organization of Medical Physicists. Chair; AAPM/ESTRO/ABG. W. Foster: None. A. Martin: None.
2648 Does Delay From Prostate Cancer Diagnosis to Treatment With Permanent Seed Implantation Increase the Risk of Disease Recurrence in Men With Clinically Localized Prostate Cancer? E. Vigneault,1,2 K. Mbodji,1 S. Aubin,2 S. Magnan,3 P. Despres,2,3 M.C. Lavallee,2 L. Beaulieu,2,3 W. Foster,2 and A.G. Martin1,2; 1Cancer Research Centre, University of Laval, Quebec, QC, Canada, 2Radiation Oncology, CHU de Quebec, Quebec, QC, Canada, 3University of Laval, Quebec, QC, Canada Purpose/Objective(s): To investigate the effect of treatment delay between prostate cancer diagnosis to treatment with low-dose-rate brachytherapy (LDR-BT) on biochemical recurrence. Materials/Methods: 929 prostate cancer patients diagnosed with localized prostate cancer were treated with Iode-125 prostate brachytherapy between 1999 and 2011. The treatment delay (TD) between disease diagnosis to LDR-BT treatment was reported. Patients were divided into three groups according to TD: TD 3 months, 3-6 months and >6 months. Biochemical relapse was determined according to Phoenix definition. Long-term biochemical recurrence-free survival (BRFS) was determined using Kaplan Meier estimates with log rank test. Cox regression model was used to analyse the predictor factors of biochemical recurrence. Results: Mean age and median follow-up were 62 years and 80 months, respectively. The percentage of patients with low and intermediate D’Amico risk group was 38.7%, 46.1%, 15.2% and 55.5%, 29%, 15.5% in TD 3 months, 3-6 months and >6 months groups (pZ0.005), respectively. The 7-and 10-year BRFS for the entire cohort was 96.4% and
International Journal of Radiation Oncology Biology Physics
2644
year. A recent survey of practicing radiation oncologists in the United States reports that almost half recommend adjuvant radiation therapy (RT) for locally advanced bladder cancer with over 90% of this group supporting the use of adjuvant RT for positive surgical margins. We sought to determine whether these physician treatment recommendations are reflected in national practice patterns. Materials/Methods: Using the National Cancer Database (NCDB), we identified patients diagnosed with non-metastatic urothelial cell or squamous cell bladder cancer from 2004 to 2014 who were treated with radical cystectomy. We studied patterns of care with regards to receipt of adjuvant RT in the overall cohort and in the positive surgical margin subgroup. Multivariable logistic regression was used to identify factors associated with receipt of adjuvant RT. Results: 46,380 patients met inclusion criteria for the overall cohort of which only 488 (1.1%) received adjuvant RT. In the overall cohort, receipt of adjuvant RT was significantly associated with squamous cell carcinoma histology (ORZ4.10, 95%CI 3.16-5.32; p<0.001), higher pathologic T stage (ORZ13.6, 95%CI 1.89-97.76; pZ0.01), and positive surgical margins (ORZ3.76, 95%CI 2.95-4.81; p<0.001). Other variables significantly associated with receipt of adjuvant RT included treatment at non-academic facilities, receipt of chemotherapy, and earlier year of diagnosis. Notably, age, race, comorbidity, and pathologic N stage did not impact receipt of adjuvant RT. There were 2,766 patients in the positive surgical margin subgroup of which only 120 (4.3%) patients received adjuvant RT. The utilization of adjuvant radiation in positive margin patients did not vary substantially over the study period. In 2004, 14/160 (8.8%) patients received adjuvant RT while 14/289 (4.8%) patients received adjuvant RT in 2014. On multivariable analysis, receipt of adjuvant RT was significantly associated with treatment at non-academic facilities, squamous cell carcinoma histology, receipt of chemotherapy, and an earlier year of diagnosis. Conclusion: In this patterns of care study, less than 5% of patients with positive surgical margins following radical cystectomy received adjuvant radiation therapy from 2004 to 2014. There appears to be a large discrepancy between the inclinations of practicing radiation oncologists and the actual practice patterns for this patient subgroup despite poor overall outcomes. These findings suggest that further work is needed to understand the risks and benefits of adjuvant RT, and may reflect a lack of multi-disciplinary care in the management of locally advanced bladder cancer. Author Disclosure: S. Venigalla: None. A.K. Chowdhry: None. D.M. Guttmann: None. B.C. Baumann: None. A. Cohen: None. R. Mamtani: None. J.P. Christodouleas: None.
100 Patients’ Experience with Brachytherapy in Bladder Implantations Performed Laparoscopically in Solitary Bladder Tumors E. van der Steen-Banasi,1 B. Oosterveld,1 C. Wijburg,2 T. Janssen,1 M. Haverkort,1 and G. Smits2; 1Radiotherapiegroep, location Arnhem, Arnhem, Netherlands, 2Rijnstate Hospital Arnhem, Arnhem, Netherlands Purpose/Objective(s): The results of the bladder sparing treatment including brachytherapy, using minimally invasive surgery to implant catheters are reported for the first 100 patients. The brachytherapy treatment was performed using initially PDR (NZ7), later with an HDR scheme. After the start in 2009 the laparoscopy technique was optimized by the use of daVinci robot platform and development of a dedicated Luneray catheter. Materials/Methods: The indication is a solitary tumor, pT1-3a, grade 2-3, no carcinoma in situ, tumor size 5 cm. After TURB and a course of external beam irradiation (40 Gy / 20 fractions, CTV including bladder and regional lymph nodes) brachytherapy follows within 10 days. A laparoscopic robot-assisted implantation procedure is performed, in selected cases combined with partial cystectomy (PC). A partial lymph node dissection (PLND) is performed if lymph node metastases are suspected on MRI. The HDR fractionation scheme was: 25 Gy in 10 fractions with 4 h interval, 3 fractions/day, prescribed at 5 mm from the catheters. An afterloader with an Ir-192 source with activity 37-13 GBq was used. Posttreatment cystoscopies and urine cytology were performed every 3 months. Results: The average tumor diameter was 2.5 cm. 31 patients underwent PC (NZ16 residual tumor), 28: PLND (resected lymph nodes nZ139 with 2 metastatic). 2-6 catheters were inserted, mean V100 was 12.5 cc. Organs at risk: bowel average D2ccZ8 Gy; D0.1ccZ15 Gy. Average hospitalization time: 6.4 days mainly due to irradiation time, is significantly reduced compared to the open procedure (15.4 days, NZ97). There was practically no blood loss or wound healing problems. Compared to the open procedure there was a significant reduction in catheter accessibility problems during irradiation. Implant quality parameters were comparable to the open procedure. 17 patients developed toxicity (CTCAE v 4): acute G3-5: delirium (NZ3), ileus (NZ1) pulmonary embolism (NZ1), fatal myocardial infarction (NZ1); late G2-3: hematuria (NZ3), urinary urgency (NZ3), lymphedema (NZ2), bladder necrosis (NZ1), recurrent cystitis (NZ1), hydronephrosis (NZ1). The average duration of the follow up was 2.0 y (range 1 m-7.0 y). Survival analysis was performed using the Kaplan e Meier method: 2-y local control was 80% and 2-y disease specific survival was 86%. Conclusion: Minimally invasive surgery improved patients’ post-operative recovery by reducing the amount of perioperative adverse events, shortening the hospitalization time and reducing treatment disturbances due to catheter accessibility. In addition, the patient’s well-being was improved by preventing isolated hospitalization. By using a robot platform during laparoscopy, tumor located in the previously inaccessible area of trigonum can be implanted. With the use of the HDR schedule we achieved satisfactory results with mild toxicity. Author Disclosure: E. van der Steen-Banasi: None. B. Oosterveld: None. C. Wijburg: None. T. Janssen: None. M. Haverkort: None. G. Smits: None.
2645 Adjuvant Radiation Therapy for Positive Surgical Margins Following Radical Cystectomy for Bladder Cancer: A National Patterns of Care Assessment S. Venigalla,1 A.K. Chowdhry,2 D.M. Guttmann,1 B.C. Baumann,3 A. Cohen,4 R. Mamtani,4 and J.P. Christodouleas3; 1Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 2 University of Rochester School of Medicine, Rochester, NY, 3University of Pennsylvania, Department of Radiation Oncology, Philadelphia, PA, 4 University of Pennsylvania, Department of Medical Oncology, Philadelphia, PA Purpose/Objective(s): Bladder cancer patients with a positive surgical margin after radical cystectomy have a median recurrence free survival of less than one
2646 A Comparative Dosimetric Feasibility Study of Robotic Radiosurgery, Volumetric Modulated Arc Therapy, and High DoseeRate Brachytherapy in the Delivery of a Focal Integrated Boost for Low Risk Prostate Cancer D.D. Vignarajah, Y.M. Tsang, P. Nariyangadu, H. Tharmalingam, G. Lowe, R. Alonzi, and P. Hoskin; Mount Vernon Cancer Centre, London, United Kingdom Purpose/Objective(s): Dose escalation to a dominant lesion with adjacent prostate sparing is a new approach to radical radiotherapy in early stage prostate cancer. We have used a focal integrated boost using high dose rate (HDR) brachytherapy and in this study ascertain whether HDR dosimetry can be achieved with robotic radiosurgery (RS) and volumetric modulated arc therapy (VMAT). Materials/Methods: Twelve patients who required histologically confirmed isolated disease correlating with a solitary focus on multiparametric MRI were included. Volumes were defined on planning CT and MRI. CTV1 was the prostate +/- base of seminal vesicles. CTV2 was the dominant lesion seen on multiparametric MRI. An additional 3mm margin, isotropic but avoiding rectum, was added to form PTV1 and 2 respectively. A single dose of 15Gy was prescribed to PTV1 and 21Gy to PTV2 as per the trial protocol. RS and VMAT plans were optimized using brachytherapy constraints. Planning objectives were V100>95% for PTVs 1 and 2. Urethral constraints were D10%<20.8Gy, D30%<22Gy and V28.5Gy Z 0. Rectal constraints were
Volume 99 Number 2S Supplement 2017
Poster Viewing E271
Abstract 2646 Planning parameters D10% Urethra D30% Urethra D2cc Rectum V150% PTV2 V200% PTV2 V19Gy PTV1 Conformity Index PTV boost Gradient Index (R50%)
Brachytherapy Mean (95%CI)
RS Mean (95%CI)
VMAT Mean (95%CI)
19.2Gy (18.1-20.3) 18.3Gy (17.3-19.2) 10.4Gy (9.7-11.1) 36.4% (31.9-40.9) 9.9% (6.1-13.7) 59.0% (52.9-65.2) 4.30 (3.03-5.56)
18.2Gy (17.5-18.9) 17.7Gy (17.0-18.4) 11.6Gy (11.0-12.3) 0 0 41.3% (33.4-49.3) 1.98 (1.53-2.43)
17.6Gy (16.5-18.6) 16.5Gy (15.9-17.1) 10.6Gy (10.2-10.9) 0 0 9.0% (7.4-10.6) 1.08 (1.07-1.09)
2.87 (2.75-3.00)
4.01 (3.77-4.24)
3.88 (3.75-4.02)
D2cc <15Gy and V19Gy Z 0cc. For each planning objective, Kruskal-Wallis ANOVA was performed to detect any significant difference between the three techniques, followed by the Bonferroni-type multiple comparison. Results: The mean PTV2 volume was 11.2cc (95%CI 7.5-14.9); PTV1 62.2cc (95%CI 50.4-74.0); mean rectal volume 33.6cc (95%CI 50.4-74.0); and mean urethral volume 2.0cc (95%CI 1.7-2.2). All techniques achieved the planning objectives, except for one brachytherapy plan which failed to achieve the V100>95% PTV1 objective. Organ at risk constraints were met in all 3 techniques. RS and VMAT plans managed to achieve lower urethral doses compared to brachytherapy although RS had the highest rectal D2cc. The conformity index was significantly better using the VMAT and RS compared to brachytherapy (p<0.05). The latter however had a superior gradient index (p<0.05). Brachytherapy delivered significant areas of high dose reflected in the V150%, V200% and equivalent uniform dose, which were unattainable with RS and VMAT. The V19Gy for the remainder of the gland, reflecting prostate sparing, was consequently higher. Conclusion: It is feasible to deliver an integrated focal boost in prostate monotherapy with HDR brachytherapy, RS and VMAT. Brachytherapy achieves significantly higher intraprostatic doses at the expense of decreased normal prostate sparing. Author Disclosure: D.D. Vignarajah: None. Y. Tsang: None. P. Nariyangadu: None. H. Tharmalingam: None. G. Lowe: None. R. Alonzi: None. P. Hoskin: Travel Expenses; Ain Shams University, American College of Radiology, Australian Brachytherapy group, ECCO, ESTRO. COUNCIL; Royal College of Radiologists. Advisory committees; NICE; ESTRO, Radiotherapy and Oncology.
2647 The Risk of Second Malignancies after Seed Migration in Prostate Cancer Patients Treated With I-125 Free Seeds Brachytherapy E. Vigneault,1,2 K. Martell,3 D. Taussky,4 S.M. Husain,5 G. Delouya,4 K. Mbodji,1 S. Magnan,6 P. Despres,2,6 M.C. Lavallee,2 S. Aubin,2 L. Beaulieu,2,6 W. Foster,2 and A.G. Martin1,2; 1Cancer Research Centre, University of Laval, Quebec, QC, Canada, 2Radiation Oncology, CHU de Quebec, Quebec, QC, Canada, 3University of Calgary, Calgary, AB, Canada, 4Universite de Montreal, Montreal, QC, Canada, 5Tom Baker Cancer Centre, Calgary, AB, Canada, 6University of Laval, Quebec, QC, Canada Purpose/Objective(s): To evaluate the risk of second malignancies after seed migration in prostate cancer patients treated with I-125 free seeds brachytherapy. Materials/Methods: Data from 2067 prostate cancer patients treated with I-125 free seeds brachytherapy in three Canadian centers were analyzed. Kaplan-Meier method was used to estimate the 5- and 7-year biochemical relapse-free and overall survival between patients who experienced or not seed migration. Results: Mean age and Median follow-up was 64 years and 44 (range 1147) months, respectively. Seed migration occurred in 365 of 2067 patients (17.7%). The 5-, 7-year biochemical relapse-free and overall survival for the entire cohort was 96%, 91.7% and 95.9%, 93.7%, respectively. Second malignancies occurred in 4 of 365 patients (1.1%) and 21 of 1702 patients (1.2%) in patients with or without seed migration, respectively (pZ0.827).
Lung cancer represented the most frequent second malignancy observed and occurred in 6 patients, all in the no seed migration group. The other second malignancies observed in the no seed migration group included: larynx (3 patients), colon (2 patients), esophagus (2), pancreatic (2), renal, myeloma, glioblastoma, non-Hodgkin’s lymphoma (1) and 2 unknown. In the seed migration group, the second malignancies observed were chronic myeloid leukemia (1), colo-rectal cancer (2) and nasopharynx (1). Conclusion: These short-term results do not support an increased risk of second malignancies, particularly lung cancer with seed migration after I-125 free seeds brachytherapy for prostate cancer patients. Due to the low rate of second malignancies observed in this cohort, further studies with longer follow-up are required to better correlate seed migration and second malignancies. Author Disclosure: E. Vigneault: Independent Contractor; CHUQ L’Hotel Dieu de Que´bec. Honoraria; Abbvie. Advisory Board; Abbvie. K. Martell: None. D. Taussky: None. S.M. Husain: None. G. Delouya: Partner; YAD Technologies. Research Grant; Janssen, Astellas, Ferring, Bayer. Honoraria; Janssen, Astellas, Ferring, Bayer. Advisory Board; Janssen, Astellas, Ferring, Bayer. Travel Expenses; Janssen, Astellas, Ferring, Bayer; CARO. K. Mbodji: None. S. Magnan: None. P. Despres: None. M. Lavallee: None. S. Aubin: None. L. Beaulieu: Research Grant; Elekta, Philips Medical. Royalty; Standard Imaging Inc. Patent/License Fees/Copyright; Standard Imaging Inc. Officer and Board Member; Canadian Organization of Medical Physicists. Chair; AAPM/ESTRO/ABG. W. Foster: None. A. Martin: None.
2648 Does Delay From Prostate Cancer Diagnosis to Treatment With Permanent Seed Implantation Increase the Risk of Disease Recurrence in Men With Clinically Localized Prostate Cancer? E. Vigneault,1,2 K. Mbodji,1 S. Aubin,2 S. Magnan,3 P. Despres,2,3 M.C. Lavallee,2 L. Beaulieu,2,3 W. Foster,2 and A.G. Martin1,2; 1Cancer Research Centre, University of Laval, Quebec, QC, Canada, 2Radiation Oncology, CHU de Quebec, Quebec, QC, Canada, 3University of Laval, Quebec, QC, Canada Purpose/Objective(s): To investigate the effect of treatment delay between prostate cancer diagnosis to treatment with low-dose-rate brachytherapy (LDR-BT) on biochemical recurrence. Materials/Methods: 929 prostate cancer patients diagnosed with localized prostate cancer were treated with Iode-125 prostate brachytherapy between 1999 and 2011. The treatment delay (TD) between disease diagnosis to LDR-BT treatment was reported. Patients were divided into three groups according to TD: TD 3 months, 3-6 months and >6 months. Biochemical relapse was determined according to Phoenix definition. Long-term biochemical recurrence-free survival (BRFS) was determined using Kaplan Meier estimates with log rank test. Cox regression model was used to analyse the predictor factors of biochemical recurrence. Results: Mean age and median follow-up were 62 years and 80 months, respectively. The percentage of patients with low and intermediate D’Amico risk group was 38.7%, 46.1%, 15.2% and 55.5%, 29%, 15.5% in TD 3 months, 3-6 months and >6 months groups (pZ0.005), respectively. The 7-and 10-year BRFS for the entire cohort was 96.4% and