Prostate specific antigen bounce after radioactive seed implantation followed by external beam radiation for prostate cancer

Purpose: Prostate specific antigen (PSA) may temporarily increase following radiotherapy for prostate cancer without signaling cancer recurrence. We describe this phenomenon which is called PSA bounce. Materials and Methods: From 1984 to 1995, 779 stage T1T2N0 cancer cases were treated with simultaneous radiotherapy with a (125)iodine prostate implant followed by external beam radiation. Median pretreatment PSA was 7.7 ng./ml. (range 0.3 to 188). PSA bounce was defined as an increase of 0.1 ng./ml. or greater above the preceding PSA level after simultaneous radiation followed by a subsequent decrease below that level. Disease-free status was defined as the ability to achieve and maintain posttreatment PSA 0.2 ng./ml. or less. Results: PSA bounce was observed in 35% of men (273 of 779). Median time to PSA bounce was 18 months from the time of implant and 92% of bounces were observed within 36 months. Median pre-bounce PSA was 0.7 ng./ml. (range 0.1 to 8.9) and median bounce height (increase above the pre-bounce level) was 0.4 ng./ml. (range 0.1 to 15.8). No distinguishing characteristics were observed between men with PSA bounce and those with cancer recurrence, and bounce had no prognostic significance relative to recurrence. Conclusions: PSA bounce is common following seed implantation for prostate cancer. It produces anxiety in men previously treated for prostate cancer and confounds the diagnosis of recurrence.