Researchers in Japan believe they have identified a link between sexual intercourse and PSA bounce following prostate cancer (PCa) brachytherapy.

In a study of 154 PCa patients followed up for at least 24 months after I-125 brachytherapy, Masashi Matsushima, MD, and colleagues at the Keio University School of Medicine in Tokyo found that a higher intercourse satisfaction domain score on the International Index of Erectile Function-15 (IIEF-15) questionnaire independently predicted an increased risk of PSA bounce.

At a median of 18 months after I-125 seed implantation, 38 men (24.7%) experienced PSA bounce, defined as a PSA rise of at least 0.4 ng/mL above an initial PSA nadir followed by a subsequent decline to or below the initial nadir without treatment. Of the 154 patients, 77 completed the IIEF-15 questionnaire 18 months after brachytherapy.

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Compared with men who did not experience PSA bounce, the PSA-bounce group had higher IIEF-15 erectile function and orgasmic function domain scores and a higher total IIEF-15 score before and after brachytherapy, the researchers reported online ahead of print in the International Journal of Urology. In multivariate analysis, only the intercourse satisfaction score at 18 months after brachytherapy was significantly associated with PSA bounce. Compared with a score below 3, a score of 3 or higher was associated with significant 5-fold increased odds of PSA bounce.

Based on their results, they researchers stated that they support a hypothesis that ejaculation as a result of sexual intercourse might cause PSA bounce.

Compared with the non-PSA-bounce group, the PSA bounce group had significantly higher proportions of patients younger than 70 years (78.9% vs. 45.7%) and those with Gleason 6 or less tumors (84.2% vs. 67.2%), according to the researchers.