Biochemical/clinical Significance Of Post-treatment Prostate-specific Antigen Bounce For Prostate Cancer Patients Treated With External Beam Radiation

In the epub online version of Cancer, Dr. Eric Horwitz and associates report that the PSA bounce noted in 20-30% of patients following external radiotherapy for prostate cancer (CaP) increases the risk of biochemical failure, but not clinical failure.

The study included 4,839 patients from nine institutions treated for stage T1b, T1c and T2N0M0 CaP between 1986 and 1995. All patients received a minimum of 60Gy to the prostate. Seventy percent of participants were treated with conventional radiotherapy and 30% with conformal techniques. A post-treatment bounce was defined by a minimal rise in PSA of 0.4ng/ml over a 6-month follow-up period, followed by a decrease in PSA of any degree. Biochemical failure was defined by the ASTRO criteria and clinical failure was defined as documentation of local, regional or distant disease recurrence.

A post-treatment PSA bounce was observed in 978 patients (20%). Of these, 721 experienced one bounce and 257 had multiple bounces. The biochemical no evidence of disease (bNED) control for patients with a PSA bounce was 58% vs. 72% for non-bounce patients at 10 years. However, a significant difference for clinical distant failure, cause-specific survival and overall survival between bounce and non-bounce patients was not found. The authors point out that there was significant attrition in the study, with 3,796 patients at risk at 3 years, decreasing to 342 patients still at risk and under observation at 10 years. The median size of the bounce was greater for patients receiving <70 Gy than >70Gy, although this did not correlate with significant differences in bNED status. Also, the radiotherapy dose did not correlate with the frequency or number of bounces. When controlling for the effect of pre-treatment PSA, Gleason score, and radiotherapy dose in multivariate analysis, the effect of a bounce remained statistically significant.

By Christopher P. Evans, M.D.

Cancer 2006 - 10.1002/cncr.22183
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