Postoperative prostate-specific antigen as a prognostic indicator in patients with margin-positive prostate cancer, undergoing adjuvant radiotherapy after radical prostatectomy

Abstract

Objectives To identify a population of patients within the group with positive surgical margins after radical prostatectomy who would benefit in terms of improved local control of disease by the administration of adju- vant radiation therapy to the prostate bed. Methods Postoperative prostate-specific antigen (PSA) values were evaluated in 45 patients with margin-pos- itive (MP) disease who underwent adjuvant radiotherapy within 6 months of surgery. All patients were clini- cally T1 -2 MO, and pNO. A cutoff of 0.5 ng/mL or less was used as the level below which PSA was considered undetectable. The mean follow-up time from date of radiation was 33 months. Results In 30 of 45 (67%) patients, PSA levels did drop to undetectable levels postoperatively. In 15 of 45 (33%) patients postoperative PSA levels did not drop to undetectable levels. In the group with detectable post- operative PSA, 12 of 15 (80%) failed adjuvant radiotherapy as determined by a progressive increase in PSA levels in a mean time of 0.95 years (range, 4 months to 2.02 years; median, 0.92 years). When postoperative PSA reached undetectable levels, only 10 of 30 (33%) failed treatment, with a mean time to failure of 2.1 years (range, 4 months to 7.8 years; median, 3.31 years). Conclusions The data would suggest that patients who are MP, but attain an undetectable PSA level post-operatively accompanied by a progressive delayed increase in PSA, probably represent a group with local disease recurrence in the prostate fossa, whereas patients whose PSA levels are detectable postoperatively may represent a group with microscopic metastatic disease or a combination of local recurrence and distant disease or large volume local persistent disease. It is in the group of patients in whom the postoperative PSA decreased to undetectable levels that adjuvant radiotherapy may be effective in controlling local progression of prostate cancer through improved local control, as indicated by a durable decrease in PSA values to undetectable levels in roughly two thirds of these patients. Longer follow-up of these patients will be required to determine whether this improved local control will translate into improved survival.