Time to achieve a prostate specific antigen nadir of 0.2 ng./ml. after simultaneous irradiation for prostate cancer

Purpose: A prostate specific antigen (PSA) cutoff point of 0.2 ng./ml. has been suggested as the standard definition of disease freedom for curative treatment of localized prostate cancer. The time to achieve this goal after irradiation was determined in this study. Materials and Methods: From August 1992 to December 1996, 539 consecutive men with clinical stage T1T2NX prostate cancer who had a minimum 5-year PSA followup and achieved a PSA nadir of 0.2 ng./ml. without hormones were evaluated. All patients were treated with simultaneous irradiation with a transperineal prostate (125)iodine implant, followed by external beam irradiation. Time to achieve a PSA of 0.2 ng./ml. was retrospectively calculated from the date of implantation in all men and according to various factors. Recurrence was defined as a subsequent increase above a PSA of 0.2 ng./ml. Minimum followup was 5 years (median 6.5, range 5 to 9). Results: In all 539 men the median time to a PSA nadir of 0.2 ng./ml. was 27 months, while 534 (99%) achieved this level by 60 months of followup. Median time to achieve this PSA goal was 20 and 39 months in patients without and with a PSA bounce, respectively. Pretreatment PSA, disease status and ultimately PSA bounce, Gleason score and stagehad little or no effect on time to a PSA of 0.2 ng./ml. Conclusions: With rare exceptions to be potentially cured of prostate cancer by simultaneous irradiation men must achieve a PSA nadir of 0.2 ng./ml. within 5 years of implantation. Failure to reach this goal by 60 months of followup almost always indicates persistent disease.