The use of radiotherapy for patients with isolated elevation of serum prostate specific antigen following radical prostatectomy

Purpose: An analysis was performed to assess the outcome of patients who received radiotherapy for isolated elevation of serum prostate specific antigen (PSA) levels following radical retropubic prostatectomy. Materials and Methods: Forty-six patients were initially treated for localized prostate cancer with radical retropubic prostatectomy following negative pelvic lymphadenectomy. These patients had detectable serum PSA 6 or more months postoperatively. No patient had other clinical evidence of recurrent disease as determined by history, physical examination, bone scan, computerized tomography of the abdomen and pelvis, chest radiographs, complete blood cell counts and serum chemistry profiles. The patients received prostate bed irradiation using 10 MV. x-rays and a 4-field approach. Doses ranged from 60.0 to 67.0 Gy. in 1.8 to 2.0 Gy. fractions. Freedom from failure after radiotherapy was defined as maintaining a PSA of 0.3 ng./ml. or less without hormonal intervention. 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 radiotherapy. Patients receiving radiation doses of 64 Gy. or more had more favorable response rates than those receiving lesser doses. Conclusions: Isolated elevations of serum PSA following prostatectomy reflect residual disease. Radiotherapy administered to the prostate bed effectively decreased serum PSA in approximately half of the cases. This effect appears to be accomplished by eradicating tumor cells in the prostate bed.