Is patient age a factor in the occurrence of prostate-specific antigen bounce phenomenon after external beam radiotherapy for prostate cancer?

Objectives. To evaluate the effect of patient age on the occurrence of prostate-specific antigen (PSA) "bounce" after external beam radiotherapy (EBRT) for prostate cancer. Methods. In this study, 964 patients received EBRT alone for prostate cancer between April 1987 and January 1998 who had been followed for at least 12 months. Prostate-specific antigen values were obtained every 3 to 6 months after radiotherapy. Median overall follow-up was 48 months. Prostate-specific antigen bounce was defined as an initial increase in serum PSA of at least 0.5 ng/mL, followed by a decrease to prebounce baseline serum PSA values, all within 60 months after EBRT. Biochemical failure was defined as three consecutive increases in posttreatment PSA concentration after achieving a nadir. Multivariate Cox regression analysis was performed to evaluate the influences of age, pretreatment PSA concentration, Gleason score (determined at biopsy), clinical T stage classification, and radiation dose on PSA bounce-free survival and biochemical disease-free survival, with P <0.05 considered statistically significant. Results. Twelve percent of the patients developed a PSA bounce. Age was not associated with the occurrence of a PSA bounce (P = 0.63), the magnitude of the PSA bounce (P = 0.90), or the duration of the PSA bounce (P = 0.39). Patients who had PSA bounce had a statistically significant higher biochemical disease-free survival than those who did not (P = 0.00004). Conclusions. In our study, age was not predictive of PSA bounce. However, younger patients with a rising PSA after radiotherapy should be followed closely for evidence of biochemical failure.