THE USE OF RADIOTHERAPY FOR PATIENTS WITH ISOLATED ELEVATION OF SERUMPROSTATE-SPECIFIC ANTIGEN FOLLOWING RADICAL PROSTATECTOMY

Purpose: An analysis was performed to assess the outcome of patients w ho received radiotherapy for isolated elevation of serum prostate spec ific antigen (PSA) levels following radical retropubic prostatectomy. Materials and Methods: Forty-six patients were initially treated for l ocalized prostate cancer with radical retropubic prostatectomy followi ng negative pelvic lymphadenectomy. These patients had detectable seru m PSA 6 or more months postoperatively. No patient had other clinical evidence of recurrent disease as determined by history, physical exami nation, bone scan, computerized tomography of the abdomen and pelvis, chest radiographs, complete blood cell counts and serum chemistry prof iles. The patients received prostate bed irradiation using 10 MV. x-ra ys and a 4-field approach. Doses ranged from 60.0 to 67.0 Gy. in 1.8 t o 2.0 Gy. fractions. Freedom from failure after radiotherapy was defin ed as maintaining a PSA of 0.3 ng./ml. or less without hormonal interv ention. Results: In 27 of the 46 patients (59%) PSA had decreased to 0 .3 ng./ml. or less at last measurement without hormonal intervention. The freedom from failure rate was 50% at 3 and 5 years. More favorable responses to salvage radiotherapy occurred in patients with low grade tumors and serum PSA 1.1 ng./ml, or less at initiation of radiotherap y. Patients receiving radiation doses of 64 Gy. or more had more favor able response rates than those receiving lesser doses. Conclusions: Is olated elevations of serum PSA following prostatectomy reflect residua l disease. Radiotherapy administered to the prostate bed effectively d ecreased serum PSA in approximately half of the cases. This effect app ears to be accomplished by eradicating tumor cells in the prostate bed .