0 Clinical Investigation PI1 SO360-3016( 97 ) 00320-9 EQUIVALENT S-YEAR bNED IN SELECT PROSTATE CANCER PATIENTS MANAGED WITH SURGERY OR RADIATION THERAPY DESPiTE EXCLUSION OF THE SEMINAL VESICLES FROM THE CTV ANTHONY V. D’AMIC~, M.D., PH.D., * RICHARD WHITTINGTON, M.D.,’ IRVING KAPL,AN, M.D.,* CLA~R BEARD, M.D., * DELRAY SCHULTZ, PH.D., 9 S. BRUCE MALKOWIC~, M.D., z JOHN E. TOMASZEWSKI, M.D.,l ALAN WEIN, M.D.: AND C. NORMAN COLEMAN, M.D.* *Harvard Medical School, Joint Center for Radiation Therapy, Boston, MA 0221.5; Hospital of the University 04’Pennsylvania. ‘Department of Radiation Oncology, *Department of Urology. ‘IDepartment of Pathology; $University of Millersville. Department of Mathematic> Purpose: Prostate Specific Antigen (PSA) failure free survival was determined for selectprostate cancer patients managed definitively with external beam radiation therapy to the prostate only or radical retropubic prostatec- tomy. Methods and Materials: A logistic regression multivariable analysis evaluating the variables of PSA, biopsy GIeason score, and &&al stage was used to evaIuate the endpoint of pathoiogic seminal vesich? invasion (SVI) in 749 consecutive prostate cancer patients managed with a radical retropubk prostatectomy. In a s&group of 332 surgicaIly and 197 radiation managed patients who did not have the cIinicaI predictors of WI, PSA faiIure free survival (bNED) was determined. Comparisons were made using the log rank test between surgicaIIy and radiation managed patients in this subgroup. In this subgroup, radiation managed patients were treated to a median dose of 66 Gy (66-70 Gy) to the prostate only. Resulk The pretreatment PSA ( > 10 rig/ml ), biopsy GIeason score ( z7), and clinical stage ( T2b, 2c, or 3 1 were found to be sign&ant independent predictors (JJ< 0.001) of SVI. Only 2% of patients without any of these factors had SVI and 17% had extracapsular extension (15% microscopic; 2% macroscopic). In tkis subgroup the S-year bNED rates were equivalent [ 84 vs. 89% (JJ= 0.67)] for surgically and radiation managed patients, respectively. Concitions: Conventional dose externaI beam radiation therapy directed at the prostate akme resukd in s-year bNED rates equivalent to surgery on retrospective comparison in patients with clinical stage Tl,2a, PSA 5 10 ng/mI, and biopsy Gleason 5 6 prostate cancer.0 1997 Elsevier ScienceInc. Prostate Cancer, Clinical target volume, Prostate specific antigen, Gleason score, Radiation therapy. INTRODUCTION Seminal vesicle rddiation has been traditionally adminis- tered for all or part of the treatment plan in the radioth- erapeutic management of clinically localized prostate can- cer in many centers. Yet, it is well known that increasing the target volume to include the seminal vesicles increases the rectal volume radiated to prescription dose thereby increasing rectal toxicity (6, 16). Using the PSA infor- mation now available in conjunction with the biopsy Glea- son score and clinical stage has improved our ability to more accurately predict the risk of pathologic involvement of the seminal vesicles ( 5, Id), In addition, the incidence of both node positive disease and seminal vesicle invasion (SW ) noted at the time of prostatectomy has decreased with the use of PSA based screening ( 12). Therefore, a reassessment of the clinical target volume may be appro- priate when planning a course of external beam radiation therapy in some carefully selected patients. The goals of this study were first. to use a multivariable analysis on a surgical data base to assess the pretreatment clinical factors that predict for pathologic involvement of the seminal vesicles. The second goal was to report the rdte of seminal vesicle invasion (SW ), macroscopic, and microscopic extracapsular extension ( ECE) in pa- tients who have or who lack the pretreatment clinical factors that predict for SW. Finally, S-year bNED rates are reported for the group of patients lacking the pre- treatment clinical predictors of SVI who were treated with external beam radiation therapy to the prostate only or with a radical retropubic prostatectomy to assess PSA failure-free survival in patients managed with one of these two treatments. To be presented at the 39th Annual meeting of the American Center for Radiation Therapy. 330 Brookline ‘\v~xue. .%h floor, Society for Therapeutic Radiology and Oncology. Boston, MA 022 15. Reprint requests to: Anthony V. D’Amico. M.D.. Ph.D., Joint Accepted for publication 28 April IW?. 33.5