POSTOPERATIVE PROSTATE-SPECIFIC ANTIGEN AS A PROGNOSTIC INDICATOR IN PATIENTS WITH MARGIN-POSITIVE PROSTATE-CANCER, UNDERGOING ADJUVANT RADIOTHERAPY AFTER RADICAL PROSTATECTOMY

Objectives. To identify a population of patients within the group with positive surgical margins after radical prostatectomy who would benef it in terms of improved local control of disease by the administration of adjuvant radiation therapy to the prostate bed. Methods. Postopera tive prostate-specific antigen (PSA) values were evaluated in 45 patie nts with margin-positive (MP) disease who underwent adjuvant radiother apy within 6 months of surgery, All patients were clinically 71-2M0, a nd pN0. A cutoff of 0.5 ng/mL or less was used as the level below whic h PSA was considered undetectable. The mean follow-up time from date o f radiation was 33 months. Results. In 30 of 45 (67%) patients, PSA le vels did drop to undetectable levels postoperatively. In 15 of 45 (33% ) patients postoperative PSA levels did not drop to undetectable level s, In the group with detectable postoperative PSA, 12 of 15 (80%) fail ed adjuvant radiotherapy as determined by a progressive increase in PS A 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 level s, only 10 of 30 (33%) failed treatment, with a mean time to failure o f 2.1 years (range, 4 months to 7.8 years; median, 3.31 years). Conclu sions. The data would suggest that patients who are MP, but attain an undetectable PSA level postoperatively accompanied by a progressive de layed increase in PSA, probably represent a group with local disease r ecurrence in the prostate fossa, whereas patients whose PSA levels are detectable postoperatively may represent a group with microscopic met astatic disease or a combination of local recurrence and distant disea se or large volume local persistent disease. It is in the group of pat ients in whom the postoperative PSA decreased to undetectable levels t hat adjuvant radiotherapy may be effective in controlling local progre ssion 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 tran slate into improved survival.