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Prophylactic versus therapeutic alpha blockers in the management of short term urinary morbidity following permanent prostate brachytherapy
Proceedings of the 44th Annual ASTRO Meeting
Purpose/Objective: Seventeen radiation oncologists (one observer for each Institution) participated in a dummy run within the Italian AIRO PROS 01-02 prospective trial evaluating rectal toxicity after conformal radiotherapy for prostate cancer. Materials/Methods: Four patients were considered (3 patients for radical conformal radiotherapy and 1 patient for postprostatectomy radiotherapy): an anatomically based definition of rectum extension (caudal limit: one slice above the anal verge; cranial limit: one slice below the point where the rectum turns into the sigmoid colon) was previously accepted by the observers. Physicians were asked to draw the external contour of the rectal wall on CT slices (5 mm step) on Cadplan (Varian Dosetek) 3D treatment planning system (TPS). This system was chosen because its image resolution is worse than the other TPS used by the Institutions involved; the contouring uncertainty may be estimated to be smaller with other systems than Cadplan. For each patient two different isocentric conformal techniques were planned (4-field and 6-field, 18 MV X-Rays) and an ICRU total dose of 76 Gy was prescribed. 3/4 patients presented minimum/moderate artifacts due to the presence of a small amount of contrast liquid in the rectum; the degree of filling of the rectum ranged from zero to moderate and bladder was full for all patients. Rectum dose statistics (mean, median and maximum rectal dose), volume and DVHs were calculated for each observer and for both techniques. For DVH analysis, V40, V45, V50, V55, V60, V65, V70, V75 (defined as the percentage of rectal volume receiving at least 45, 50, 55, 60, 65, 70, 75 Gy) were evaluated. Results: The contouring uncertainty was analyzed in different ways. Differences in cranial and caudal border definitions were measured. Only 1/17 observer presented an average deviation from the most probable caudal limit greater than 5 mm; however, for the surgically treated patient, 5/17 showed a difference at the cranial and/or caudal borders greater than 5 mm. When assessing contouring uncertainty in terms of standard deviation (SD) from the average value, the impact was significant on dose statistics and DVH. Systematic (inter-observer) and random (intra-observer) components of contouring uncertainty were separated: intra-observer variability was found to be dominant. However, 3/17 observers showed a prevalence of inter-observer variability (one due to systematic deviation in caudal limit and two due to a very large dimension of the rectum in the most caudal portion). These were excluded from the analysis and the observers were asked to re-define the rectal contours. Final results showed average SD values of 3-3.5% and 2-2.5% for V50-V60 and V65-V75 respectively and of 2-2.5 Gy for mean/median dose; the average values of SD for the only three radically irradiated patients were slightly lower. Conclusions: Our investigation showed an acceptable consistency on rectal DVH and dose statistics between the Institutions involved in the AIRO PROS 01-02 trial. On the other hand, the impact of contouring uncertainty is significant and should be taken into account when attempting to define reliable confidence levels of rectal dose-volume constraints.
2080
Prophylactic Versus Therapeutic Alpha Blockers in the Management of Short Term Urinary Morbidity Following Permanent Prostate Brachytherapy
G.S. Merrick1, W.M. Butler1, K.E. Wallner2, J.H. Lief3, R.W. Galbreath3 1
Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV, 2University of Washington, Seattle, WA, 3Wheeling Jesuit University, Wheeling, WV, 4Department of Pathology, Wheeling Hospital, Wheeling, WV Purpose/Objective: In this study, we evaluated the influence of prophylactic versus therapeutic alpha blockers on urinary morbidity in patients undergoing permanent prostate brachytherapy. Multiple clinical and treatment parameters were evaluated to identify factors associated with acute urinary morbidity. Materials/Methods: 234 consecutive patients underwent transperineal ultrasound guided permanent prostate brachytherapy on one of two prospective randomized studies from October 1999 through February 2001 using either palladium-103 or iodine-125 for clinical T1b-T2b (1997 AJCC) adenocarcinoma of the prostate gland at either the Schiffler Cancer Center (SCC) or the Puget Sound Veterans Administration Hospital/University of Washington (PSVAH). The mean and median follow-up was 8.8 ⫾4.6 and 6 months respectively (range 1–18 months). In 142 patients, an ␣-blocker was initiated prior to implantation and continued at least until the International Prostate Symptom Score (I-PSS) returned to baseline levels while 92 patients either did not receive an ␣-blocker or received a therapeutic ␣-blocker following implantation because of urinary obstructive/irritative symptoms. Clinical and treatment parameters evaluated for urinary morbidity included the prophylactic versus therapeutic usage of ␣-blockers, patient age, preimplant I-PSS, prostate ultrasound volume, the utilization of neoadjuvant hormonal manipulation, the utilization of supplemental external beam radiation therapy, the choice of isotope, the urethral dose, and multiple dosimetric quality indicators (D90, V100,200). Catheter dependency and the duration of ␣-blocker dependency were also evaluated. Results: For each of the 2 institutions, the I-PS score peaked at 1 month following implantation. Patients receiving a prophylactic ␣-blocker returned to within 1 point of the antecedent value at a mean of 4 months and a median of 3 months. For those patients not receiving prophylactic ␣-blockers, the I-PS score returned to the antecedent value at a mean and median of 10 months and 6 months, respectively. 81.2% of patients received prophylactic ␣-blockers (102/125) and 140/179 (78.2%) patients receiving ␣-blockers remained medication dependent at the conclusion of the study. The incidence of prolonged urinary catheter dependency (greater than 3 days) and the need for a postimplant TUIP/TURP were not affected by ␣-blocker usage. Based on a Cox regression analysis of the clinical and treatment parameters evaluated for urinary morbidity, only the implanting institution and the difference between the preimplant I-PSS and the 1 month I-PSS were predictive for time to return to the referent zone. Conclusions: Prophylactic utilization of ␣-blockers results in significantly less urinary morbidity than either the absence or therapeutic utilization of ␣-blockers. In patients receiving prophylactic ␣-blockers, the I-PS score normalized significantly faster but there was little or no impact on urinary retention or the ultimate need for a postimplant transurethral resection.
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Purpose/Objective: Seventeen radiation oncologists (one observer for each Institution) participated in a dummy run within the Italian AIRO PROS 01-02 prospective trial evaluating rectal toxicity after conformal radiotherapy for prostate cancer. Materials/Methods: Four patients were considered (3 patients for radical conformal radiotherapy and 1 patient for postprostatectomy radiotherapy): an anatomically based definition of rectum extension (caudal limit: one slice above the anal verge; cranial limit: one slice below the point where the rectum turns into the sigmoid colon) was previously accepted by the observers. Physicians were asked to draw the external contour of the rectal wall on CT slices (5 mm step) on Cadplan (Varian Dosetek) 3D treatment planning system (TPS). This system was chosen because its image resolution is worse than the other TPS used by the Institutions involved; the contouring uncertainty may be estimated to be smaller with other systems than Cadplan. For each patient two different isocentric conformal techniques were planned (4-field and 6-field, 18 MV X-Rays) and an ICRU total dose of 76 Gy was prescribed. 3/4 patients presented minimum/moderate artifacts due to the presence of a small amount of contrast liquid in the rectum; the degree of filling of the rectum ranged from zero to moderate and bladder was full for all patients. Rectum dose statistics (mean, median and maximum rectal dose), volume and DVHs were calculated for each observer and for both techniques. For DVH analysis, V40, V45, V50, V55, V60, V65, V70, V75 (defined as the percentage of rectal volume receiving at least 45, 50, 55, 60, 65, 70, 75 Gy) were evaluated. Results: The contouring uncertainty was analyzed in different ways. Differences in cranial and caudal border definitions were measured. Only 1/17 observer presented an average deviation from the most probable caudal limit greater than 5 mm; however, for the surgically treated patient, 5/17 showed a difference at the cranial and/or caudal borders greater than 5 mm. When assessing contouring uncertainty in terms of standard deviation (SD) from the average value, the impact was significant on dose statistics and DVH. Systematic (inter-observer) and random (intra-observer) components of contouring uncertainty were separated: intra-observer variability was found to be dominant. However, 3/17 observers showed a prevalence of inter-observer variability (one due to systematic deviation in caudal limit and two due to a very large dimension of the rectum in the most caudal portion). These were excluded from the analysis and the observers were asked to re-define the rectal contours. Final results showed average SD values of 3-3.5% and 2-2.5% for V50-V60 and V65-V75 respectively and of 2-2.5 Gy for mean/median dose; the average values of SD for the only three radically irradiated patients were slightly lower. Conclusions: Our investigation showed an acceptable consistency on rectal DVH and dose statistics between the Institutions involved in the AIRO PROS 01-02 trial. On the other hand, the impact of contouring uncertainty is significant and should be taken into account when attempting to define reliable confidence levels of rectal dose-volume constraints.
2080
Prophylactic Versus Therapeutic Alpha Blockers in the Management of Short Term Urinary Morbidity Following Permanent Prostate Brachytherapy
G.S. Merrick1, W.M. Butler1, K.E. Wallner2, J.H. Lief3, R.W. Galbreath3 1
Schiffler Cancer Center, Wheeling Hospital, Wheeling, WV, 2University of Washington, Seattle, WA, 3Wheeling Jesuit University, Wheeling, WV, 4Department of Pathology, Wheeling Hospital, Wheeling, WV Purpose/Objective: In this study, we evaluated the influence of prophylactic versus therapeutic alpha blockers on urinary morbidity in patients undergoing permanent prostate brachytherapy. Multiple clinical and treatment parameters were evaluated to identify factors associated with acute urinary morbidity. Materials/Methods: 234 consecutive patients underwent transperineal ultrasound guided permanent prostate brachytherapy on one of two prospective randomized studies from October 1999 through February 2001 using either palladium-103 or iodine-125 for clinical T1b-T2b (1997 AJCC) adenocarcinoma of the prostate gland at either the Schiffler Cancer Center (SCC) or the Puget Sound Veterans Administration Hospital/University of Washington (PSVAH). The mean and median follow-up was 8.8 ⫾4.6 and 6 months respectively (range 1–18 months). In 142 patients, an ␣-blocker was initiated prior to implantation and continued at least until the International Prostate Symptom Score (I-PSS) returned to baseline levels while 92 patients either did not receive an ␣-blocker or received a therapeutic ␣-blocker following implantation because of urinary obstructive/irritative symptoms. Clinical and treatment parameters evaluated for urinary morbidity included the prophylactic versus therapeutic usage of ␣-blockers, patient age, preimplant I-PSS, prostate ultrasound volume, the utilization of neoadjuvant hormonal manipulation, the utilization of supplemental external beam radiation therapy, the choice of isotope, the urethral dose, and multiple dosimetric quality indicators (D90, V100,200). Catheter dependency and the duration of ␣-blocker dependency were also evaluated. Results: For each of the 2 institutions, the I-PS score peaked at 1 month following implantation. Patients receiving a prophylactic ␣-blocker returned to within 1 point of the antecedent value at a mean of 4 months and a median of 3 months. For those patients not receiving prophylactic ␣-blockers, the I-PS score returned to the antecedent value at a mean and median of 10 months and 6 months, respectively. 81.2% of patients received prophylactic ␣-blockers (102/125) and 140/179 (78.2%) patients receiving ␣-blockers remained medication dependent at the conclusion of the study. The incidence of prolonged urinary catheter dependency (greater than 3 days) and the need for a postimplant TUIP/TURP were not affected by ␣-blocker usage. Based on a Cox regression analysis of the clinical and treatment parameters evaluated for urinary morbidity, only the implanting institution and the difference between the preimplant I-PSS and the 1 month I-PSS were predictive for time to return to the referent zone. Conclusions: Prophylactic utilization of ␣-blockers results in significantly less urinary morbidity than either the absence or therapeutic utilization of ␣-blockers. In patients receiving prophylactic ␣-blockers, the I-PS score normalized significantly faster but there was little or no impact on urinary retention or the ultimate need for a postimplant transurethral resection.
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