Patterns and fate of PSA bouncing following 3D-CRT

Purpose: The goals of this study were to quantify the frequency of post-tre atment prostate-specific antigen (PSA)-level bouncing following three-dimen sional conformal radiation therapy (3D-CRT) for prostate cancer and to iden tify any relationships that may exist between bouncing activity and biochem ical control (bNED). Methods: Between May 1989 and July 1995, 306 patients were treated with 3D- CRT alone. All patients had 6 or more post-treatment PSA levels and at leas t 5 years of PSA follow-up. The median total follow-up and total dose to th e center of prostate was 79 months and 74 Gy, respectively. A bounce was de fined by a minimum rise in PSA of 0.4 ng/mL over a 6-month period, followed by a drop in PSA of any magnitude. Estimates of bNED control rates were ma de using Kaplan-Meier methodology and comparisons were made using the log-r ank test. Multivariate analysis of bNED control predictors was accomplished using a stepwise Cox proportional hazards model. Results: Nearly one third of the patients experienced at least one bounce. Bouncers were found to present with higher pretreatment PSA levels and were treated with lower dose levels to the center of prostate. Five-year bNED c ontrol estimates for nonbouncers vs. bouncers were 69% and 52%, respectivel y (p = 0.0024). After controlling for dose and pretreatment PSA level, tota l number of bounces emerged as a significant predictor of bNED control (p = 0.02). Conclusions: pouncing PSA levels occur in approximately one third of the pa tients treated with 3D-CRT alone, with bouncing occurring at a constant rat e from 2 to 5 years post-treatment. Bouncing is associated with lower radia tion dose levels, higher pretreatment PSA levels, and decreased bNED contro l. Nearly half of the bouncers are bNED controlled; thus, clinicians should not use bouncing as a sole indicator of relapse. (C) 2001 Elsevier Science Inc.