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Daily Variations in Rectal and Bladder Doses with Image Guided Prostate Radiotherapy and the Feasibility of Adaptive Radiotherapy Planning
I. J. Radiation Oncology d Biology d Physics
S348
2399
Volume 72, Number 1, Supplement, 2008
Prospective Evaluation of Gastrointestinal (GI) and Genitourinary (GU) Toxicity of Salvage Radiotherapy (RT) to the Prostate Bed for Patients with PSA Relapse after Radical Prostatectomy (RP)
M. Pearse1, R. Choo2, C. Danjoux3, S. Gardner3, G. Morton3, E. Szumacher3, A. Loblaw3, P. Cheung3 1
Auckland City Hospital, Auckland, New Zealand, 2Mayo Clinic, Department of Radiation Oncology, Rochester, MN, 3Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada Purpose/Objective(s): To evaluate acute and late toxicity of salvage RT to the prostate bed for patients with PSA relapse after RP. Materials/Methods: A total of 75 patients were accrued between 1998 and 2002 for a Phase II study to evaluate the efficacy of a combined, sequential, treatment of salvage RT plus 2-year androgen suppression (LHRH analogue) for patients with PSA relapse after RP. Clinical target volume of RT was limited to the prostate bed. A total dose of 60-66 Gy (2 Gy/fraction) was delivered with a 4-field box technique, using 18 MV photons. Acute and late RT morbidity was prospectively assessed, using the NCI Expanded Common Toxicity Criteria version 2. For acute morbidity, prevalence was examined. For late morbidity, time-adjusted incidences of Grade $2 and Grade 3 toxicity were calculated, using the cumulative incidence method. Predictive factors for late toxicity were analyzed with Cox proportional hazards regression. Results: Median age was 63 years at the time of RP. Median time from RP to RT was 36.2 months. As of 3/2005, median follow-up was 45.1 months. 75 and 72 patients were available for acute and late toxicity analysis, respectively. 12% and 40% had pre-existing GI and GU dysfunction prior to RT, respectively. Acute toxicity was common, but mild (GI toxicity: 71%, 11%, and 3% for Grade 1, and 2, and 3, respectively; GU toxicity: 71%, 9%, and 3% for Grade 1, 2, and 3, respectively). 5% experienced Grade 3 acute GI or GU acute toxicity (2: diarrhea, 1: urinary frequency, 1: urinary incontinence). Using the maximum late GI and GU toxicity score registered at any point of time during the follow-up, 42%, 8%, and 1% reported Grade 1, 2, and 3 late GI toxicity, respectively; 49%, 24%, and 6% scored Grade 1, 2, and 3 late GU toxicity respectively. 7% had Grade 3 late toxicity (1: proctitis, 2: hematuria, 1: incontinence, and 1: urethral stricture and frequency). None had Grade 4 late toxicity. Cumulative incidences of Grade $2 late GI and GU toxicity at 36 months were 8.7%, and 22.6%, respectively. Cumulative incidences of Grade 3 late GI and GU toxicity at 36 months were 1.6% and 2.8%, respectively. On multivariate analysis, the severity of acute GU toxicity was a significant predictor (p \ 0.0001) for late GU toxicity after adjusting for pre-existing GU dysfunction. None was a predictor for late GI toxicity. Of 26 with pre-existing urinary incontinence prior to RT, deterioration, no change, and improvement of incontinence were reported in 8%, 42%, and 50%, respectively, at 30 months. Among 45 with full urinary continence prior to RT, 69% remained continent, while 29% and 2% reported Grade 1 and 2 incontinence, respectively. Conclusions: Salvage RT for PSA relapse after RP was generally well tolerated. Grade $3 late GI or GU toxicity was uncommon. Author Disclosure: M. Pearse, None; R. Choo, None; C. Danjoux, None; S. Gardner, None; G. Morton, None; E. Szumacher, None; A. Loblaw, None; P. Cheung, None.
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Daily Variations in Rectal and Bladder Doses with Image Guided Prostate Radiotherapy and the Feasibility of Adaptive Radiotherapy Planning
R. Jacob, X. Wu, C. M. Dobelbower, J. Carlisle, R. Y. Kim, R. Popple, J. B. Fiveash University of Alabama at Birmingham, Birmingham, AL Purpose/Objective(s): Study daily variations in bladder and rectal volumes during a course of prostate radiotherapy (RT) and compare cumulative doses to these structures using relevant dose-volume parameters. Determine if adaptive RT (ART) is necessary in patients (pts) receiving a course of fractionated RT. Study the feasibility of performing corrective ART planning based on cumulative data obtained from daily Megavoltage images (MVCT) during the first 3 weeks of RT. Materials/Methods: Two patients (pts) who received prostate RT with 60 Gy/20 fractions (fr) were studied. Pts were treated on a helical Tomotherapy unit after applying daily shifts in all planes. Daily MVCT images obtained for image guidance were extended to cover the entire rectum and bladder. MV image sets were reloaded and the shifts used for daily treatment were applied. The rectum and bladder were recontoured and doses recalculated for each fr. Variations in volumes and dose-volume parameters of the bladder and rectum were recorded. Cumulative doses to target, rectum and bladder from the first 15 RT fr were compared with the planned doses. Adaptive plans were performed to correct for doses to the target, bladder and rectum. Results: Mean rectal volumes for pts 1 and 2 were 85.95 cc and 84.67 cc during simulations and 136.8 cc and 127.9 cc during RT. Mean rectal volume covered by the prescription isodose was 14.3 % less than planned in pt 1 and 46.6% more in pt 2. The mean rectal D50, D33 and D17 were 88 ± 3%, 93.5 ± 6.3% and 94 ± 6.2% of the planned doses for pt 1 and 108.5 ± 7.8%, 110.7 ± 10.6% and 106.5 ± 6.1% of the planned doses for pt 2. Mean dose to "hottest 10 cc" of the rectum was higher by 10.4% in pt1 and 24.4% pt 2. Mean bladder volumes during the RT course were 6.8% less (166.2 ± 18.7 cc) in pt 1and 4.5% more (124.3 ± 39.6 cc) in pt 2 compared to their planning scans. Mean bladder volumes covered by the prescription isodose were higher by 14.3 ± 27% in pt 1 and 12.5 ± 31% in pt 2. The mean bladder D50, D25 and D15 values were 107.9 ± 14.3%, 103.5 ± 4.6% and 103.5 ± 4.2% of planned doses for pt 1 and 93.5 ± 5.2%, 100.3 ± 6.9% and 99.4 ± 5.6% for pt 2 respectively. The dose to "hottest-10cc" of bladder was 1.3% and 11.5% more than planned. Cumulative values for rectal D50, D33, D17 and bladder D50, D25 and D15 from first 15 fr were determined. Dose volume constraints for ART planning were determined by subtracting delivered dose from the original plan. A new TomoIMRT plan was generated to deliver the remaining dose over 5 fr. Conclusions: The impact of daily variations in critical organ volumes and doses are less likely to be clinically significant during a protracted course of RT; but significant if hypofractionation is planned. The feasibility of performing corrective ART with Tomotherapy planning based on cumulative dose data to critical structures obtained from daily MVCT image sets was confirmed. Author Disclosure: R. Jacob, None; X. Wu, None; C.M. Dobelbower, None; J. Carlisle, None; R.Y. Kim, None; R. Popple, None; J.B. Fiveash, None.
S348
2399
Volume 72, Number 1, Supplement, 2008
Prospective Evaluation of Gastrointestinal (GI) and Genitourinary (GU) Toxicity of Salvage Radiotherapy (RT) to the Prostate Bed for Patients with PSA Relapse after Radical Prostatectomy (RP)
M. Pearse1, R. Choo2, C. Danjoux3, S. Gardner3, G. Morton3, E. Szumacher3, A. Loblaw3, P. Cheung3 1
Auckland City Hospital, Auckland, New Zealand, 2Mayo Clinic, Department of Radiation Oncology, Rochester, MN, 3Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada Purpose/Objective(s): To evaluate acute and late toxicity of salvage RT to the prostate bed for patients with PSA relapse after RP. Materials/Methods: A total of 75 patients were accrued between 1998 and 2002 for a Phase II study to evaluate the efficacy of a combined, sequential, treatment of salvage RT plus 2-year androgen suppression (LHRH analogue) for patients with PSA relapse after RP. Clinical target volume of RT was limited to the prostate bed. A total dose of 60-66 Gy (2 Gy/fraction) was delivered with a 4-field box technique, using 18 MV photons. Acute and late RT morbidity was prospectively assessed, using the NCI Expanded Common Toxicity Criteria version 2. For acute morbidity, prevalence was examined. For late morbidity, time-adjusted incidences of Grade $2 and Grade 3 toxicity were calculated, using the cumulative incidence method. Predictive factors for late toxicity were analyzed with Cox proportional hazards regression. Results: Median age was 63 years at the time of RP. Median time from RP to RT was 36.2 months. As of 3/2005, median follow-up was 45.1 months. 75 and 72 patients were available for acute and late toxicity analysis, respectively. 12% and 40% had pre-existing GI and GU dysfunction prior to RT, respectively. Acute toxicity was common, but mild (GI toxicity: 71%, 11%, and 3% for Grade 1, and 2, and 3, respectively; GU toxicity: 71%, 9%, and 3% for Grade 1, 2, and 3, respectively). 5% experienced Grade 3 acute GI or GU acute toxicity (2: diarrhea, 1: urinary frequency, 1: urinary incontinence). Using the maximum late GI and GU toxicity score registered at any point of time during the follow-up, 42%, 8%, and 1% reported Grade 1, 2, and 3 late GI toxicity, respectively; 49%, 24%, and 6% scored Grade 1, 2, and 3 late GU toxicity respectively. 7% had Grade 3 late toxicity (1: proctitis, 2: hematuria, 1: incontinence, and 1: urethral stricture and frequency). None had Grade 4 late toxicity. Cumulative incidences of Grade $2 late GI and GU toxicity at 36 months were 8.7%, and 22.6%, respectively. Cumulative incidences of Grade 3 late GI and GU toxicity at 36 months were 1.6% and 2.8%, respectively. On multivariate analysis, the severity of acute GU toxicity was a significant predictor (p \ 0.0001) for late GU toxicity after adjusting for pre-existing GU dysfunction. None was a predictor for late GI toxicity. Of 26 with pre-existing urinary incontinence prior to RT, deterioration, no change, and improvement of incontinence were reported in 8%, 42%, and 50%, respectively, at 30 months. Among 45 with full urinary continence prior to RT, 69% remained continent, while 29% and 2% reported Grade 1 and 2 incontinence, respectively. Conclusions: Salvage RT for PSA relapse after RP was generally well tolerated. Grade $3 late GI or GU toxicity was uncommon. Author Disclosure: M. Pearse, None; R. Choo, None; C. Danjoux, None; S. Gardner, None; G. Morton, None; E. Szumacher, None; A. Loblaw, None; P. Cheung, None.
2400
Daily Variations in Rectal and Bladder Doses with Image Guided Prostate Radiotherapy and the Feasibility of Adaptive Radiotherapy Planning
R. Jacob, X. Wu, C. M. Dobelbower, J. Carlisle, R. Y. Kim, R. Popple, J. B. Fiveash University of Alabama at Birmingham, Birmingham, AL Purpose/Objective(s): Study daily variations in bladder and rectal volumes during a course of prostate radiotherapy (RT) and compare cumulative doses to these structures using relevant dose-volume parameters. Determine if adaptive RT (ART) is necessary in patients (pts) receiving a course of fractionated RT. Study the feasibility of performing corrective ART planning based on cumulative data obtained from daily Megavoltage images (MVCT) during the first 3 weeks of RT. Materials/Methods: Two patients (pts) who received prostate RT with 60 Gy/20 fractions (fr) were studied. Pts were treated on a helical Tomotherapy unit after applying daily shifts in all planes. Daily MVCT images obtained for image guidance were extended to cover the entire rectum and bladder. MV image sets were reloaded and the shifts used for daily treatment were applied. The rectum and bladder were recontoured and doses recalculated for each fr. Variations in volumes and dose-volume parameters of the bladder and rectum were recorded. Cumulative doses to target, rectum and bladder from the first 15 RT fr were compared with the planned doses. Adaptive plans were performed to correct for doses to the target, bladder and rectum. Results: Mean rectal volumes for pts 1 and 2 were 85.95 cc and 84.67 cc during simulations and 136.8 cc and 127.9 cc during RT. Mean rectal volume covered by the prescription isodose was 14.3 % less than planned in pt 1 and 46.6% more in pt 2. The mean rectal D50, D33 and D17 were 88 ± 3%, 93.5 ± 6.3% and 94 ± 6.2% of the planned doses for pt 1 and 108.5 ± 7.8%, 110.7 ± 10.6% and 106.5 ± 6.1% of the planned doses for pt 2. Mean dose to "hottest 10 cc" of the rectum was higher by 10.4% in pt1 and 24.4% pt 2. Mean bladder volumes during the RT course were 6.8% less (166.2 ± 18.7 cc) in pt 1and 4.5% more (124.3 ± 39.6 cc) in pt 2 compared to their planning scans. Mean bladder volumes covered by the prescription isodose were higher by 14.3 ± 27% in pt 1 and 12.5 ± 31% in pt 2. The mean bladder D50, D25 and D15 values were 107.9 ± 14.3%, 103.5 ± 4.6% and 103.5 ± 4.2% of planned doses for pt 1 and 93.5 ± 5.2%, 100.3 ± 6.9% and 99.4 ± 5.6% for pt 2 respectively. The dose to "hottest-10cc" of bladder was 1.3% and 11.5% more than planned. Cumulative values for rectal D50, D33, D17 and bladder D50, D25 and D15 from first 15 fr were determined. Dose volume constraints for ART planning were determined by subtracting delivered dose from the original plan. A new TomoIMRT plan was generated to deliver the remaining dose over 5 fr. Conclusions: The impact of daily variations in critical organ volumes and doses are less likely to be clinically significant during a protracted course of RT; but significant if hypofractionation is planned. The feasibility of performing corrective ART with Tomotherapy planning based on cumulative dose data to critical structures obtained from daily MVCT image sets was confirmed. Author Disclosure: R. Jacob, None; X. Wu, None; C.M. Dobelbower, None; J. Carlisle, None; R.Y. Kim, None; R. Popple, None; J.B. Fiveash, None.