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Results of a prospective multi-institutional phase II trial (RTOG 98–05) of transrectal ultrasound guided permanent radioactive implantation of the prostate for definitive management of localized adenocarcinoma of the prostate
S184
I. J. Radiation Oncology
● Biology ● Physics
Volume 60, Number 1, Supplement, 2004
Results: The median follow– up was 61 months with 32 patients at risk at 144 months. Overall and disease specific survival at 12 years is 84% and 93%, respectively. BCR using the ASTRO and Houston definitions are 78% and 76%, respectively. BCR–ASTRO by risk stratification (Zelefsky classification) was 84% for low risk patients, 78% for intermediate risk patients and 68% for high risk patients (p ⫽ .0001). Cox regression identified that pretreatment PSA (.0001), Gleason score (.0001) and the D90 dose (.004) were significant to predict BCR–ASTRO, while clinical stage (.422), the addition of hormones (.874), the addition of external radiation (.095) and isotope selection (.218) were insignificant factors predicting BCR-ASTRO. Analysis of BCR–ASTRO patients identified disease–specific survival of 65% with a PSA doubling time of less than 12 months versus 92% with a PSA doubling time ⱖ12 months (p ⫽ .0001). Conclusions: This is one of the largest series reporting 12-year outcomes following PPB. BCR outcomes can be predicted by a patients pretreatment PSA values and Gleason score; therefore risk-stratification by these clinical factors statistically segregates outcomes. Nonetheless, implant dosimetry continues to predict for BCR. The addition of adjuvant therapies such as hormones and external radiation do not predict for BCR, yet this was not prospectively controlled. In patients with biochemical failure, it appears that the PSA doubling time of less than 12 months is an important predictor for survival. This may encourage more aggressive salvage treatment in those patients.
89
Does Local Control Impact Prostate Cancer Specific Survival (PCSS) Within the First 10 Years Following Brachytherapy
R. G. Stock,1 N. N. Stone,2,1 J. A. Cesaretti1 1 Radiation Oncology, Mount Sinai School of Medicine, New York, NY, 2Urology, Mount Sinai School of Medicine, New York, NY Purpose/Objective: In theory, local failure following prostate cancer therapy can lead to metastases and eventual death from the disease. Treatment and disease related factors which contribute to local control should, in turn, affect prostate cancer specific survival (PCSS). PCSS was analyzed in relationship to pre-treatment and treatment parameters as well as to other outcome endpoints to shed light on the relationship of local control and death from prostate cancer within 10 years following prostate brachytherapy. Materials/Methods: 1,510 patients with t1 to t3 prostate cancer and median age of 66 years (range: 39 – 88) were treated with permanent seed implantation from 1990 to 2002. They were followed from 1 to 13 years (median - 6). Pre-treatment parameters were as follows: PSA (range: 0.3–300, median - 7.35), stage ( ⱕt2a in 65% , ⱖt2b in 35% ), score (ⱕ6 in 69%, 7 in 21% and 8 –10 in 10%). Patients were treated with implant alone (I-125 or Pd-103) in 41%, hormonal therapy and implant in 27%, and implant and external beam ( ⫾ hormonal therapy) in 32%. BED calculations were performed using an alpha/beta ratio of 2 based on the D90 and external beam doses to enable various isotopes and treatment approaches to be compared. For example, a D90 of 140Gy for I-125 ⫽ BED of 147, a D90 of 100Gy (NIST 99) for Pd-103 ⫽ BED of 133, 45Gy of external beam ⫽ BED of 63. PSA failure was calculated using the ASTRO definition. 2 years post-treatment prostate biopsies (6 cores) were recommended for all patients. Results: The actuarial freedom from PSA failure, PCSS and overall survival at 10 years were 76%, 91% and 67%. 403 patients underwent post-treatment biopsies at 2 years and 15% were positive. Of the pretreatment factors, Gleason score had the most significant effect on PCSS. PCSS at 10 years was 93% for score ⱕ6, 85% for 7 and 86% for 8 –10 (p ⬍ 0.0001). PCSS at 10 years was 90% for PSA ⱕ10, 88% for ⬎10 –20, and 91% for ⬎20 (p ⫽ 0.28). PCSS at 10 yrs was 99% for stage ⱕt2a and 85% for stage ⱖt2b (p ⫽ 0.007). Low, moderate and high risk patients had 10 year PCSS rates of 99%, 87% and 90%, respectively (p ⫽ 0.0006). Treatment approach did not significantly affect PCSS (p ⫽ 0.13). In the 130 pts who experienced a PSA failure, the 10 yr PCSS was 76% compared to 99% for those without failure (p ⬍ 0.0001). PSA doubling time in those patients with a PSA failure had a profound effect on PCSS. In univariate analysis, doubling time cut-points of 3, 6 and 12 months all significantly affected PCSS (all p values ⬍0.0001). Actuarial 10 year PCSS for patients with doubling times ⱕ3 mos, ⱕ6 months and ⱕ12 months were 0%, 30% and 61%, respectively. Although dose (using a BED cut-point of 150) had a significant effect on PSA failure (p ⫽ 0.0001), it had no effect on PCSS with rates of 97% and 95% for doses ⱕ150 and ⬎150, respectively (p ⫽ 0.9). Although biopsy results significantly correlated with PSA failure (p<0.0001), they did not significantly affect PCSS. Patients with negative biopsies had a PCSS of 98% versus 83% for patients with a positive biopsy (p ⫽ 0.3). Conclusions: The above data suggest that although factors which are closely related to local control such as dose and biopsy outcomes significantly correlate with PSA failure, they do not impact 10 year PCSS rates. This, along with the strong correlation of PSA doubling times and Gleason score with PCSS suggest that many patients dying of prostate cancer within 10 years of therapy probably have microscopic disseminated disease at diagnosis. Longer follow-up will be needed to determine if those with local failure and low BED values will eventually succumb to the disease.
90
Results of a Prospective Multi-Institutional Phase II Trial (RTOG 98 – 05) of Transrectal Ultrasound Guided Permanent Radioactive Implantation of the Prostate for Definitive Management of Localized Adenocarcinoma of the Prostate
C. A. Lawton,1 M. DeSilvio,2 W. R. Lee,3 L. Gomella,4 D. Grignon,5 M. Gillin,6 G. Morton,7 T. Pisansky,8 H. Sandler9 Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, 2RTOG, Philadelphia, PA, 3Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC, 4Urology, Thomas Jefferson University, Philadelphia, PA, 5 Pathology, Wayne State University, Detroit, MI, 6Radiation Oncology, MD Anderson, Houston, TX, 7Radiation Oncology, Toronto-Sunnybrook Regional Cancer Center, Toronto, ON, Canada, 8Radiation Oncology, Mayo Clinic, Rochester, MN, 9 Radiation Oncology, University of Michigan, Ann Arbor, MI 1
Purpose/Objective: This prospective trial was opened by the Radiation Therapy Oncology Group (RTOG) in 1998 to evaluate the effectiveness of transrectal ultrasound guided permanent implantation of the prostate compared to historical data of prostatectomy or external beam radiotherapy within a cooperative group setting with special attention to the quality assurance standards of brachytherapy.
Proceedings of the 46th Annual ASTRO Meeting
Materials/Methods: One hundred and one patients were accrued to this protocol, which closed in April 2000. Accrued patients had low risk prostate cancer (T1-2, GS⬍6, PSA ⬍10) and underwent an I125 permanent implantation of the prostate (145 Gy TG-43). Results: Of 101 patients, 97 are eligible and analyzable. Of the eligible patients, 96 had brachytherapy data and 95 had adequate follow up for evaluation. Median follow up was 41 months (range 4.5 months to 60.1 months). Ninety-four of the eligible patients had an implant that was delivered either per protocol or with an acceptable minor variation. The 3-year cumulative incidence rate of any failure is 9.8% per the protocol definition of failure (two consecutive rises above the nadir with the rise in PSA exceeding 1 ng/ml above the nadir or positive biopsy). The 3-year biochemical failure rates using the protocol definition and the ASTRO definition were 4.3% and 3.2% respectively. Acute grade 3 or higher toxicity was seen in eight patients, four of the eight were GU toxicity, 2 sexual, and the others hemorrhage. There were no grade 4 or grade 5 acute toxicities. Fifty patients experienced grade 2 toxicity, 44 of the 50 were genitourinary toxicities. Late grade 3 or higher toxicity was noted in 2 patients with grade 3 toxicity both genitourinary and no grade 4 or grade 5 toxicity. Conclusions: This prospective multi-institutional brachytherapy trial was completed successfully with acceptable quality assurance and early results comparable with single institution series. The toxicities are consistent with other reported series. With this trial, the RTOG has demonstrated its capacity to perform a prospective quality assured prostate brachytherapy trial and provides a positive outlook for the feasibility of subsequent cooperative group trials, including the active Phase III trial RTOG P-0232 examining the role of supplemental external beam radiotherapy for prostate brachytherapy.
91
Treatment of Intermediate Risk Prostate Cancer with Brachytherapy Monotherapy: A Review of the H Lee Moffitt Cancer Center Experience
J. F. Torres-Roca, A. B. Cantor, S. Shukla, M. E. Montejo, J. Friedland, J. D. Seigne, R. Heysek, M. De Marco, S. Kelley, J. Pow-Sang Interdisciplinary Oncology, H Lee Moffitt Cancer Center, Tampa, FL Purpose/Objective: The role of brachytherapy in the treatment of intermediate risk prostate cancer (GS ⫽ 7 and/or PSA more than 10.0 ng/ml but less than 20 ng/ml, CS ⬍T3a) is controversial. In general, these patients are at a higher risk for extracapsular and seminal vesicle extension than favorable risk patients (GS ⬍7, PSA ⬍10 ng/ml, CS ⬍T2b). Therefore, in theory brachytherapy monotherapy may risk undertreating the cancer that has extended beyond the confines of the prostate. For this reason, a number of institutions have adopted the policy of adding a course of supplemental pelvic irradiation (45 Gy) that precedes or follows the implant. However, there is no clear consensus as to whether brachytherapy monotherapy with a permanent seed implant is sufficient treatment for these patients. To this end the RTOG has initiated a prospective Phase III trial that randomizes intermediate risk patients between brachytherapy alone vs external beam radiotherapy (45 Gy) followed by a brachytherapy boost. At the H. Lee Moffitt Cancer Center the policy until 2001 was to treat all intermediate risk patients with permanent seed brachytherapy monotherapy without supplemental external beam radiotherapy. We have reviewed our experience to determine whether we could identify a subset of patients within intermediate risk prostate cancer that could be treated successfully with brachytherapy monotherapy. Furthermore we wanted to identify whether markers of low volume disease (number of positive cores, percentage of cores positive etc) were prognostic factors within this risk group. Materials/Methods: Between July 1993 and June 1999 a total of 466 patients were treated with a permanent seed implant at our institution. Under an IRB approved protocol, we reviewed the charts of all 466 patients and identified intermediate risk patients (as defined above). A total of 135 patients fitted the selection criteria for intermediate risk prostate cancer and a total of 91 had a minimum of 36 months of follow up. Median follow up for the whole cohort was 50.5 months with a range of 37–100 months. Biochemical failure was defined using the ASTRO definition. All patients were treated with an Iodine-125 transperineal permanent prostate seed implant using RapidStrand (Amersham) except for three patients that were treated with loose seeds. A total dose of 160 Gy (pre-TG-43) was delivered to the prostate. Results: The biochemical five-year failure free survival (bFFS) for the whole cohort was 84.8 %. Within this subset of patients, only perineural invasion was a significant prognostic factor. The 5-year biochemical failure free survival of patients with and without perineural invasion was 66.7 % vs 89.2% respectively (p ⫽ 0.018). None of the following factors were found to be significant: Gleason score 6 vs 7 (5yr bFFS 83.7% vs 85.7%), Primary Gleason grade 3 vs 4 (5yr bFFS 84.7% vs 85.7%), percentage of core positive ⬍20% vs ⬎20% (5yr bFFS 91.4% vs 82.1%, p ⫽ 0.2), number of cores positive ⬍2 vs 2 vs ⬎2 (5yr bFFS 82% vs 87.5% vs 86.2%, p ⫽ 0.83), hormone therapy vs no hormone therapy (5yr bFFS 82.7% vs 88.2%), clinical stage T1 vs T2 (5yr bFFS 87.3% vs 81.1%, p ⫽ 0.37)PSA ⬍10 vs ⬎10 (5 bFFS 0.84 vs 0.85, p ⫽ 0.961), two intermediate risk factors vs one intermediate risk factor (5 bFFS 0.90 vs 0.84, p ⫽ 0.674). Conclusions: Our data suggests that most patients with intermediate risk disease can be treated effectively with brachytherapy monotherapy. Patients with perineural invasion had a worse outcome after a permanent seed implant alone. We were unable to determine whether these patients failed because of locally uncontrolled tumor or because of distant metastases and thus it was not clear whether supplemental external beam radiation would have been beneficial.
92
Efficacy of External Beam Radiotherapy Compared to Permanent Prostate Implant in Treating Low Risk Prostate Cancer Based on Endorectal Magnetic Resonance Spectroscopy Imaging and PSA
B. Pickett,1 J. Kurhanewicz,2 F. Coakley,2 J. Pouliot,1 N. Albright,1 K. Shinohara,3 M. Roach, III1,3 1 Radiation Oncology, University of California, SF, San Francisco, CA, 2Radiology, University of California, SF, San Francisco, CA, 3Urology, University of California, SF, San Francisco, CA Purpose/Objective: Recent studies suggest that treatment of low risk prostate cancer yields similar results for patients treated with external beam radiation therapy (EBRT) to greater than 72 Gy or permanent prostate implant (PPI). These studies usually define outcome based on the ASTRO consensus definition. Unfortunately, the ASTRO definition has a relatively poor
S185
I. J. Radiation Oncology
● Biology ● Physics
Volume 60, Number 1, Supplement, 2004
Results: The median follow– up was 61 months with 32 patients at risk at 144 months. Overall and disease specific survival at 12 years is 84% and 93%, respectively. BCR using the ASTRO and Houston definitions are 78% and 76%, respectively. BCR–ASTRO by risk stratification (Zelefsky classification) was 84% for low risk patients, 78% for intermediate risk patients and 68% for high risk patients (p ⫽ .0001). Cox regression identified that pretreatment PSA (.0001), Gleason score (.0001) and the D90 dose (.004) were significant to predict BCR–ASTRO, while clinical stage (.422), the addition of hormones (.874), the addition of external radiation (.095) and isotope selection (.218) were insignificant factors predicting BCR-ASTRO. Analysis of BCR–ASTRO patients identified disease–specific survival of 65% with a PSA doubling time of less than 12 months versus 92% with a PSA doubling time ⱖ12 months (p ⫽ .0001). Conclusions: This is one of the largest series reporting 12-year outcomes following PPB. BCR outcomes can be predicted by a patients pretreatment PSA values and Gleason score; therefore risk-stratification by these clinical factors statistically segregates outcomes. Nonetheless, implant dosimetry continues to predict for BCR. The addition of adjuvant therapies such as hormones and external radiation do not predict for BCR, yet this was not prospectively controlled. In patients with biochemical failure, it appears that the PSA doubling time of less than 12 months is an important predictor for survival. This may encourage more aggressive salvage treatment in those patients.
89
Does Local Control Impact Prostate Cancer Specific Survival (PCSS) Within the First 10 Years Following Brachytherapy
R. G. Stock,1 N. N. Stone,2,1 J. A. Cesaretti1 1 Radiation Oncology, Mount Sinai School of Medicine, New York, NY, 2Urology, Mount Sinai School of Medicine, New York, NY Purpose/Objective: In theory, local failure following prostate cancer therapy can lead to metastases and eventual death from the disease. Treatment and disease related factors which contribute to local control should, in turn, affect prostate cancer specific survival (PCSS). PCSS was analyzed in relationship to pre-treatment and treatment parameters as well as to other outcome endpoints to shed light on the relationship of local control and death from prostate cancer within 10 years following prostate brachytherapy. Materials/Methods: 1,510 patients with t1 to t3 prostate cancer and median age of 66 years (range: 39 – 88) were treated with permanent seed implantation from 1990 to 2002. They were followed from 1 to 13 years (median - 6). Pre-treatment parameters were as follows: PSA (range: 0.3–300, median - 7.35), stage ( ⱕt2a in 65% , ⱖt2b in 35% ), score (ⱕ6 in 69%, 7 in 21% and 8 –10 in 10%). Patients were treated with implant alone (I-125 or Pd-103) in 41%, hormonal therapy and implant in 27%, and implant and external beam ( ⫾ hormonal therapy) in 32%. BED calculations were performed using an alpha/beta ratio of 2 based on the D90 and external beam doses to enable various isotopes and treatment approaches to be compared. For example, a D90 of 140Gy for I-125 ⫽ BED of 147, a D90 of 100Gy (NIST 99) for Pd-103 ⫽ BED of 133, 45Gy of external beam ⫽ BED of 63. PSA failure was calculated using the ASTRO definition. 2 years post-treatment prostate biopsies (6 cores) were recommended for all patients. Results: The actuarial freedom from PSA failure, PCSS and overall survival at 10 years were 76%, 91% and 67%. 403 patients underwent post-treatment biopsies at 2 years and 15% were positive. Of the pretreatment factors, Gleason score had the most significant effect on PCSS. PCSS at 10 years was 93% for score ⱕ6, 85% for 7 and 86% for 8 –10 (p ⬍ 0.0001). PCSS at 10 years was 90% for PSA ⱕ10, 88% for ⬎10 –20, and 91% for ⬎20 (p ⫽ 0.28). PCSS at 10 yrs was 99% for stage ⱕt2a and 85% for stage ⱖt2b (p ⫽ 0.007). Low, moderate and high risk patients had 10 year PCSS rates of 99%, 87% and 90%, respectively (p ⫽ 0.0006). Treatment approach did not significantly affect PCSS (p ⫽ 0.13). In the 130 pts who experienced a PSA failure, the 10 yr PCSS was 76% compared to 99% for those without failure (p ⬍ 0.0001). PSA doubling time in those patients with a PSA failure had a profound effect on PCSS. In univariate analysis, doubling time cut-points of 3, 6 and 12 months all significantly affected PCSS (all p values ⬍0.0001). Actuarial 10 year PCSS for patients with doubling times ⱕ3 mos, ⱕ6 months and ⱕ12 months were 0%, 30% and 61%, respectively. Although dose (using a BED cut-point of 150) had a significant effect on PSA failure (p ⫽ 0.0001), it had no effect on PCSS with rates of 97% and 95% for doses ⱕ150 and ⬎150, respectively (p ⫽ 0.9). Although biopsy results significantly correlated with PSA failure (p<0.0001), they did not significantly affect PCSS. Patients with negative biopsies had a PCSS of 98% versus 83% for patients with a positive biopsy (p ⫽ 0.3). Conclusions: The above data suggest that although factors which are closely related to local control such as dose and biopsy outcomes significantly correlate with PSA failure, they do not impact 10 year PCSS rates. This, along with the strong correlation of PSA doubling times and Gleason score with PCSS suggest that many patients dying of prostate cancer within 10 years of therapy probably have microscopic disseminated disease at diagnosis. Longer follow-up will be needed to determine if those with local failure and low BED values will eventually succumb to the disease.
90
Results of a Prospective Multi-Institutional Phase II Trial (RTOG 98 – 05) of Transrectal Ultrasound Guided Permanent Radioactive Implantation of the Prostate for Definitive Management of Localized Adenocarcinoma of the Prostate
C. A. Lawton,1 M. DeSilvio,2 W. R. Lee,3 L. Gomella,4 D. Grignon,5 M. Gillin,6 G. Morton,7 T. Pisansky,8 H. Sandler9 Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, 2RTOG, Philadelphia, PA, 3Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC, 4Urology, Thomas Jefferson University, Philadelphia, PA, 5 Pathology, Wayne State University, Detroit, MI, 6Radiation Oncology, MD Anderson, Houston, TX, 7Radiation Oncology, Toronto-Sunnybrook Regional Cancer Center, Toronto, ON, Canada, 8Radiation Oncology, Mayo Clinic, Rochester, MN, 9 Radiation Oncology, University of Michigan, Ann Arbor, MI 1
Purpose/Objective: This prospective trial was opened by the Radiation Therapy Oncology Group (RTOG) in 1998 to evaluate the effectiveness of transrectal ultrasound guided permanent implantation of the prostate compared to historical data of prostatectomy or external beam radiotherapy within a cooperative group setting with special attention to the quality assurance standards of brachytherapy.
Proceedings of the 46th Annual ASTRO Meeting
Materials/Methods: One hundred and one patients were accrued to this protocol, which closed in April 2000. Accrued patients had low risk prostate cancer (T1-2, GS⬍6, PSA ⬍10) and underwent an I125 permanent implantation of the prostate (145 Gy TG-43). Results: Of 101 patients, 97 are eligible and analyzable. Of the eligible patients, 96 had brachytherapy data and 95 had adequate follow up for evaluation. Median follow up was 41 months (range 4.5 months to 60.1 months). Ninety-four of the eligible patients had an implant that was delivered either per protocol or with an acceptable minor variation. The 3-year cumulative incidence rate of any failure is 9.8% per the protocol definition of failure (two consecutive rises above the nadir with the rise in PSA exceeding 1 ng/ml above the nadir or positive biopsy). The 3-year biochemical failure rates using the protocol definition and the ASTRO definition were 4.3% and 3.2% respectively. Acute grade 3 or higher toxicity was seen in eight patients, four of the eight were GU toxicity, 2 sexual, and the others hemorrhage. There were no grade 4 or grade 5 acute toxicities. Fifty patients experienced grade 2 toxicity, 44 of the 50 were genitourinary toxicities. Late grade 3 or higher toxicity was noted in 2 patients with grade 3 toxicity both genitourinary and no grade 4 or grade 5 toxicity. Conclusions: This prospective multi-institutional brachytherapy trial was completed successfully with acceptable quality assurance and early results comparable with single institution series. The toxicities are consistent with other reported series. With this trial, the RTOG has demonstrated its capacity to perform a prospective quality assured prostate brachytherapy trial and provides a positive outlook for the feasibility of subsequent cooperative group trials, including the active Phase III trial RTOG P-0232 examining the role of supplemental external beam radiotherapy for prostate brachytherapy.
91
Treatment of Intermediate Risk Prostate Cancer with Brachytherapy Monotherapy: A Review of the H Lee Moffitt Cancer Center Experience
J. F. Torres-Roca, A. B. Cantor, S. Shukla, M. E. Montejo, J. Friedland, J. D. Seigne, R. Heysek, M. De Marco, S. Kelley, J. Pow-Sang Interdisciplinary Oncology, H Lee Moffitt Cancer Center, Tampa, FL Purpose/Objective: The role of brachytherapy in the treatment of intermediate risk prostate cancer (GS ⫽ 7 and/or PSA more than 10.0 ng/ml but less than 20 ng/ml, CS ⬍T3a) is controversial. In general, these patients are at a higher risk for extracapsular and seminal vesicle extension than favorable risk patients (GS ⬍7, PSA ⬍10 ng/ml, CS ⬍T2b). Therefore, in theory brachytherapy monotherapy may risk undertreating the cancer that has extended beyond the confines of the prostate. For this reason, a number of institutions have adopted the policy of adding a course of supplemental pelvic irradiation (45 Gy) that precedes or follows the implant. However, there is no clear consensus as to whether brachytherapy monotherapy with a permanent seed implant is sufficient treatment for these patients. To this end the RTOG has initiated a prospective Phase III trial that randomizes intermediate risk patients between brachytherapy alone vs external beam radiotherapy (45 Gy) followed by a brachytherapy boost. At the H. Lee Moffitt Cancer Center the policy until 2001 was to treat all intermediate risk patients with permanent seed brachytherapy monotherapy without supplemental external beam radiotherapy. We have reviewed our experience to determine whether we could identify a subset of patients within intermediate risk prostate cancer that could be treated successfully with brachytherapy monotherapy. Furthermore we wanted to identify whether markers of low volume disease (number of positive cores, percentage of cores positive etc) were prognostic factors within this risk group. Materials/Methods: Between July 1993 and June 1999 a total of 466 patients were treated with a permanent seed implant at our institution. Under an IRB approved protocol, we reviewed the charts of all 466 patients and identified intermediate risk patients (as defined above). A total of 135 patients fitted the selection criteria for intermediate risk prostate cancer and a total of 91 had a minimum of 36 months of follow up. Median follow up for the whole cohort was 50.5 months with a range of 37–100 months. Biochemical failure was defined using the ASTRO definition. All patients were treated with an Iodine-125 transperineal permanent prostate seed implant using RapidStrand (Amersham) except for three patients that were treated with loose seeds. A total dose of 160 Gy (pre-TG-43) was delivered to the prostate. Results: The biochemical five-year failure free survival (bFFS) for the whole cohort was 84.8 %. Within this subset of patients, only perineural invasion was a significant prognostic factor. The 5-year biochemical failure free survival of patients with and without perineural invasion was 66.7 % vs 89.2% respectively (p ⫽ 0.018). None of the following factors were found to be significant: Gleason score 6 vs 7 (5yr bFFS 83.7% vs 85.7%), Primary Gleason grade 3 vs 4 (5yr bFFS 84.7% vs 85.7%), percentage of core positive ⬍20% vs ⬎20% (5yr bFFS 91.4% vs 82.1%, p ⫽ 0.2), number of cores positive ⬍2 vs 2 vs ⬎2 (5yr bFFS 82% vs 87.5% vs 86.2%, p ⫽ 0.83), hormone therapy vs no hormone therapy (5yr bFFS 82.7% vs 88.2%), clinical stage T1 vs T2 (5yr bFFS 87.3% vs 81.1%, p ⫽ 0.37)PSA ⬍10 vs ⬎10 (5 bFFS 0.84 vs 0.85, p ⫽ 0.961), two intermediate risk factors vs one intermediate risk factor (5 bFFS 0.90 vs 0.84, p ⫽ 0.674). Conclusions: Our data suggests that most patients with intermediate risk disease can be treated effectively with brachytherapy monotherapy. Patients with perineural invasion had a worse outcome after a permanent seed implant alone. We were unable to determine whether these patients failed because of locally uncontrolled tumor or because of distant metastases and thus it was not clear whether supplemental external beam radiation would have been beneficial.
92
Efficacy of External Beam Radiotherapy Compared to Permanent Prostate Implant in Treating Low Risk Prostate Cancer Based on Endorectal Magnetic Resonance Spectroscopy Imaging and PSA
B. Pickett,1 J. Kurhanewicz,2 F. Coakley,2 J. Pouliot,1 N. Albright,1 K. Shinohara,3 M. Roach, III1,3 1 Radiation Oncology, University of California, SF, San Francisco, CA, 2Radiology, University of California, SF, San Francisco, CA, 3Urology, University of California, SF, San Francisco, CA Purpose/Objective: Recent studies suggest that treatment of low risk prostate cancer yields similar results for patients treated with external beam radiation therapy (EBRT) to greater than 72 Gy or permanent prostate implant (PPI). These studies usually define outcome based on the ASTRO consensus definition. Unfortunately, the ASTRO definition has a relatively poor
S185