PD-103 BRACHYTHERAPY AND EXTERNAL-BEAM IRRADIATION FOR CLINICALLY LOCALIZED, HIGH-RISK PROSTATIC-CARCINOMA

Purpose: To summarize biochemical failure rates and morbidity of exter nal beam irradiation (EBRT) combined with palladium (Pd-103) boost for clinically localized high-risk prostate carcinoma. Methods and Materi als: Seventy-three consecutive patients with stage T2a-T3 prostatic ca rcinoma were treated from 1991 through 1994. Each patient had at least one of the following risk factors for extracapsular disease extension : Stage T2b or greater (71 patients), Gleason score 7-10 (40 patients) , prostate specific antigen (PSA) >15 (32 patients), or elevated prost atic acid phosphatase (PAP) (17 patients). Patients received 41 Gy EBR T to a limited pelvic field, followed 4 weeks later by a Pd-103 boost (prescription dose: 80 Gy). Biochemical failure was defined as a PSA g reater than 1.0 ng/ml (normal < 4.0 ng/ml). Patients whose PSA was sti ll decreasing at the last follow-up were censored at that time. Patien ts whose PSA plateaued at a value greater than 1.0 were scored as fail ures at the time the PSA first plateaued. Results: The overall, actuar ial freedom from biochemical failure at 3 years after treatment was 79 %. In Cox proportional hazard multivariate analysis, the strongest pre dictor of failure was elevated acid phosphatase (p = 0.04), followed b y PSA (p = 0.17), Stage (p = 0.23), and Gleason score (p = 0.6). Treat ment-related morbidity was usually limited to temporary, RTOG Grade 1- 2 urinary symptoms. One patient, who had both a transurethral incision of the prostate (TUIP) and a transurethral resection of the prostate (TURF), developed low-volume urinary incontinence. The actuarial poten cy rate at 3 years after implantation was 77% for 46 patients who were sexually potent prior to implant. Conclusion: Biochemical freedom fro m failure rates following combined EBRT and Pd-103 brachytherapy for c linically localized, high-risk prostate cancer compare favorably with that reported after conventional dose EBRT alone. Morbidity has been a cceptable.