PSA Bounce After Brachytherapy May Mimic Biochemical Failure

UroToday.com - At 18-24 months post-brachytherapy for prostate cancer (CaP) it is not uncommon to have a transient rise in the PSA referred to as PSA bounce. This is possibly due to the delay in cell kill from brachytherapy, but is not well understood. The American Society for Therapeutic Radiology and Oncology (ASTRO) defines biochemical failure for CaP as 3 consecutive rises in the PSA. Dr. Toledano and associates investigated whether PSA bounce might mimic the ASTRO definition of failure and report their findings in the journal Brachytherapy.

Between 1999 and 2001 295 patients were treated with brachytherapy at the Paris Institute Curie/Hospital Cochin/Hospital Necker Paris group. Enrolled patients had clinical stage T1-T2 CaP, Gleason <7 (3+4), and PSA level <15ng/ml. Mean patient age was 65 years and the prescribed dose was 145Gy. Median follow-up was 40.3 months. D90 was superior to 145Gy in almost all patients.

Results showed a PSA bounce in 161 patients (55%) of at least 0.1ng/ml; 145 men had a PSA bounce of 0.2ng/ml; 93 men had a PSA bounce of 0.4ng/ml and 43 men had a bounce of 1ng.ml. Ninety-five percent of PSA bounces were observed in the first 3 years after implantation, at a mean of 19 months.

Multivariate analysis showed only age <70 years and D90 <200 Gy as independent factors for a PSA bounce of >0.4ng/ml. Thirty-two patients (11% of the total cohort) presented 3 successive PSA increases with a significant (3 months) interval between the measurements, thereby meeting the ASTRO definition of PSA failure. Interestingly, of those 32 men 18 subsequently showed a complete normalization of their PSA without any additional treatment.

It appears that PSA bounce may overlap with the ASTRO definition of PSA failure from CaP and thereby confound those who may receive additional therapy.

By Christopher P. Evans, M.D.

Brachytherapy 2006;5:122-126
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