PSA bouncing after external beam radiation for prostate cancer with or without hormonal treatment

The purpose of this study was to find out the frequency of PSA bouncing and the factors effecting PSA bounce after external beam radiation treatment (EBRT) with or without hormonal treatment (HT) for prostate cancer and to identify any possible relationship with biochemical control.

Between March 1997 and November 2000, 72 consecutive patients with clinically localised prostate cancer were treated by EBRT with or without HT. All patients had a pretreatment PSA level, at least six post-treatment PSA levels and minimum two years of follow-up. Median follow-up for all patients was 51 months (range 25-69 months). Median radiation dose given to the center of the prostate was 70Gy (range 63-74Gy). Fifty-nine patients (82%) received adjuvant HT with median duration of six months. PSA bounce was defined as a minimal rise of 0.4ng/ml over six months (monthly rise > or =0.07 ng/ml), followed by any decrease. Biochemical failure was defined in accordance with the ASTRO consensus guidelines.

Seventeen patients (24%) experienced at least one PSA bounce. PSA bounces were more frequent in patients with T1-2 stage, pretreatment PSA <10 ng/ml, small field irradiation, radiation dose < or =70 Gy, PSA nadir > or =0.2 ng/ml and without HT. PSA bounce occurred in 54% of patients treated by EBRT only, and 17% of patients treated by EBRT and HT. Logistic regression model for multivariate analysis revealed the radiation field size as the only independent predictive factor for PSA bounce. Five-year biochemical control rates were 82% for non-bouncers and 88% for bouncers (p=0.5).

PSA bouncing occurs in approximately a quarter of patients treated with EBRT with or without HT. It is associated with pretreatment and treatment characteristics, but we did not observe any relationship with biochemical failure.