Prostate-specific antigen nadir: the optimum level after irradiation for prostate cancer.

Abstract

PURPOSEThe prostate-specific antigen (PSA) nadir that reflects potential cure of prostate cancer by irradiation has not been established. This report attempts to demonstrate the PSA nadir goal for radiotherapy.MATERIALS AND METHODSFrom January 1984 through April 1994, 536 stage T1T2NO prostate cancer patients were treated with radioactive iodine 125 (125I) prostate implants followed by external-beam radiation. All were staged node-negative: 68% by pelvic node dissection and the remainder by computed tomographic (CT) scan. The mean pretreatment PSA level was 12.4 ng/mL (median, 8.4 ng/mL; range, 0.3 to 188 ng/mL). The median follow-up duration is 40 months (range, 12 to 138). An increasing posttreatment PSA level defined recurrence.RESULTSPatients who achieved a PSA nadir < or = 0.5 ng/mL had a 95% (+/- 4%) 5-year and an 84% (+/- 12%) 10-year disease-free survival rate, compared with a 5-year disease-free survival rate of 29% (+/- 30%) for those who reached a nadir of 0.6 to 1.0 ng/mL (P = .0001). All pati...