No Worries: PSA 'Bounce' With Prostate Cancer Tied to Sex

Nick Mulcahy

April 28, 2016

Prostate-specific antigen (PSA) "bounce" — a small rise and fall in PSA level after curative radiation therapy for prostate cancer — is more common in men who are more sexually active, according to a study from Japan.

PSA bounce can be a worrisome event because it can be difficult to distinguish from biochemical recurrence, which is a larger and sustained PSA increase, according to researchers, led by Masashi Matsushima, MD, from the Keio University School of Medicine in Tokyo.

Bounces occur only in men who are treated with radiation therapy and can be ongoing for years. They do not occur after prostatectomy, which reduces PSA to undetectable levels almost immediately after surgery.

The Japanese team defines PSA bounce as an increase of at least 0.4 ng/mL from a previous PSA level, with a subsequent decline equal to or less than the initial nadir.

Several risk factors for PSA bounce after radiation have been identified, including, most consistently, younger age.

The researchers wondered if a hallmark of younger age — sexual function — was influencing bounces. So they reviewed data on 154 patients who were treated with brachytherapy for localized disease and followed for at least 24 months at their center.

As part of their care, the men had their erectile function status prospectively assessed at baseline and then repeatedly after treatment with the 15-item International Index of Erectile Function Questionnaire (IIEF).

The study was published in the March issue of the International Journal of Urology.

PSA bounce was observed in 38 (24.7%) men.

Erectile function domain scores were higher in the bounce group than in the nonbounce group, as were orgasmic function domain scores, and IIEF scores at baseline and 3, 6, 12, 18, 24, and 36 months after brachytherapy (P < .05).

Univariate analysis showed that men in the PSA bounce group were younger than those in the nonbounce group, and were more likely to have a Gleason score of 6 or less.

Notably, multivariate analysis of the 77 men with 18-month follow-up data showed that intercourse satisfaction domain score was an independent indicator of the occurrence of PSA bounce 18 months after brachytherapy (P = .008).

The researchers emphasize this finding about intercourse because they suspect that "ejaculation might cause a physiological rise in serum PSA levels."

How does ejaculation cause a PSA rise? "The contraction of pelvic muscles and periprostatic tissue might increase the chances of PSA leaking into the blood stream during ejaculation," Dr Matsushima and his team explain.

Various research backs up this idea.

For example, ejaculation in the 48 hours before PSA testing caused a significant increase in PSA levels from baseline in men 49 to 79 years of age in one study (Urology. 1996;47:511-516).

And in another study, the magnitude of PSA bounce was significantly higher after ejaculation in the previous 48 hours than after less recent ejaculation (Int J Radiat Oncol Biol Phys. 2002;5:698-702).

PSA bounce has also been tied to the degree of a man's sexual function, but that study looked only at pretreatment function (Int J Urol. 2014;21:658-663).

The Japanese study adds to this literature by reviewing men who had been treated only with brachytherapy, and looking at pre- and post-treatment sexual function, explain Dr Matsushima and colleagues.

But it is a modest contribution, said Marc Smaldone, MD, a urologic oncologist at the Fox Chase Cancer Center in Philadelphia.

 
I don't think this shows a causative relationship.
 

"I don't think this shows a causative relationship," he told Medscape Medical News. "This is a hard thing to correlate with only 2 years of follow-up."

Furthermore, the clinical significance of the findings is unclear, said Dr Smaldone.

The researchers acknowledge that it is important to identify the factors associated with PSA bounce. Bounce "often engenders considerable anxiety for both the patient and physician," they write, "and might result in unnecessary investigations, prostate biopsy, and salvage treatment."

But Dr Smaldone pointed out that the researchers had an idiosyncratic definition of PSA bounce. "It is generally defined as a 15% rise over the previous level," he said. Dr Matsushima and colleagues defined a bounce as a PSA increase of at least 0.4 ng/mL.

The relevance of this study might be somewhat limited in the United States, where the use of brachytherapy has dropped considerably in the past 20 years. "External-beam radiation has taken over," Dr Smaldone noted.

Nevertheless, when men are treated with radiation, including brachytherapy, they are inquisitive about PSA bounce. "We get asked a lot of questions about it," he added.

The study authors and Dr Smaldone have disclosed no relevant financial relationships.

Int J Urol. 2016;23:247-252. Abstract

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