Radiotherapy for Isolated Increases in Serum Prostate-Specific Antigen Levels After Radical Prostatectomy

To assess the outcome of radiotherapy in patients with increased serum prostate-specific antigen (PSA) levels 6 months or more after radical prostatectomy. In 27 Mayo Clinic patients, we examined the results of radiotherapy relative to various potentially prognostic factors during a median follow-up of 25 months. All 27 patients had no nodal involvement at the time of prostatectomy and no clinical evidence of disease, as determined by history, physical examination, a radionuclide bone scan, computed tomography of the abdomen and pelvis, chest roentgenography, complete blood cell counts, and serum chemistry profiles. With use of 10-MV photons and a four-field approach, these patients received irradiation to the prostatic bed (60 to 67 Gy in 1.8- to 2.0-Gy fractions). Levels of PSA initially decreased in 24 of the 27 patients (89%). In 16 of the 27 patients (59%), the PSA level decreased to 0.3 ng/mL or less without hormonal intervention. “Freedom from failure” (defined as the actuarial chance of maintaining a PSA level of 0.3 ng/mL or less) was 58% at 2 years and 48% at 3 years. The response to salvage radiotherapy was more favorable in patients with no tumor spread into the seminal vesicles and those with serum PSA levels of less than 1.1 ng/mL at the beginning of radiotherapy than in those with seminal vesicle involvement or higher PSA levels. In addition, patients who received radiation doses of 64 Gy or more had more favorable responses than did those who received lesser doses. Radiotherapy resulted in no severe toxicity. No patient had clinical evidence of disease at the time of this report. Isolated increases in serum PSA after prostatectomy indicate the presence of residual or recurrent disease, and radiotherapy effectively decreases the PSA in approximately half the cases. This result is achieved by eradicating residual or recurrent cancer in the postoperative tumor bed.