Purpose: To determine the results of radiotherapy (RT) to the prostate bed for a presumed local recurrence heralded by a rising prostate-specific antigen (PSA) after radical prostatectomy (RP) for adenocarcinoma of the prostate.
Methods and materials: From 1987 to 1997, 89 patients were treated by the senior author (M.S.A.) with RT to the prostate bed for a rising PSA after RP. No patients had clinical or radiographic evidence of local or distant disease. The RT technique was usually a 4-field box with fields shaped to protect normal tissues. Of the 89 patients, 36 (40%) were treated using three-dimensional conformal RT (3DRT) using beam's eye view technique; the remaining 53 patients (60%) were irradiated using a standard two-dimensional approach. The median dose was 66 Gy. Patients were followed at 3- to 6-month intervals after completing RT with a history, physical examination, and PSA. Late normal tissue toxicity was scored using Radiation Therapy Oncology Group (RTOG) criteria. An undetectable PSA was required to be considered free of prostate cancer (NED).
Results: Eighty-seven percent of patients had pathologic stage III/IV disease. Three patients had lymph node involvement. The median PSA prior to RT was 1.4 ng/mL. The median Gleason score was 7. Of the 89 patients, 64 (72%) became NED. Of these 64 patients, 47 (73%) remain NED at last follow-up (median follow-up = 48 months). The estimated 4-year disease-free survival (DFS) for all patients is 50%. The DFS at 4 years was 61% for the 3DRT patients vs. 41% for those treated without 3DRT (p = 0.006). Late complications (Grade 1/2 only), however, were significantly more common in the 3DRT group. On multivariate analysis, only dose > 65 Gy predicted for better DFS.
Conclusions: Pelvic RT may achieve sustained remission of prostate cancer for about half of patients with a rising PSA after RP, at least in the intermediate term. Doses > 65 Gy are recommended. 3DRT may offer improved disease-free survival over non-3D approaches, however, this issue requires further study.