ED Induced by Prostate Biopsy Likely 'Underestimated'

Nick Mulcahy

October 01, 2015

The various degrees of erectile dysfunction (ED) that occur after prostate biopsy with a needle through the rectum wall have "probably been underestimated," according to new research.

A new study showed a "significant decrease" in the erectile function score of most men after biopsy, and the drop was independent of age, cancer diagnosis, and previous biopsy status, report the study authors, led by Katie Murray, MD, from the University of Kansas Medical Center in Kansas City.

Although ED was recognized as a complication of prostate biopsy as early as 2001, it has not been well-established by data, unlike potential adverse events such as hematuria, pain, voiding dysfunction, and infection.

In their prospective study, Dr Murray and her team used a standard test — the International Index of Erectile Function (IIEF-5) — to evaluate 220 men with elevated levels of prostate-specific antigen (PSA) who underwent a transrectal-ultrasonography-guided prostate biopsy.

In the study cohort, median IIEF-5 score was significantly lower 1 week after biopsy than at baseline (15.5 vs 18.2; P < .001). And the score remained significantly lower at 4 weeks (17.3 vs 18.4; P = .008) and 12 weeks (16.9 vs 18.4; P = .004).

The team does not, however, say that the needle caused physical damage in this nerve-intensive area that led to ED. "The exact cause of this effect is yet to be determined," they write.

The study was published in the August issue of BJU International.

"Psychological stress" likely contributes to the ED, writes Brian Helfand, MD, from the University of Chicago, in an accompanying editorial. The men in this study who had a benign biopsy had a fairly quick return to baseline in terms of their erectile function (after 1 week, as a group), even though some men reported lower scores for up to 3 weeks.

Dr Helfand points out that a study he was involved in showed that a diagnosis of prostate cancer "can influence a man's erectile function after prostate biopsy" (BJU Int. 2013;111:38-43).

The literature on this subject is mixed, with some studies finding and some not finding that biopsy induces ED, he adds. Nevertheless, Dr Helfand suggests that "patients should be counseled on the possibility of relatively short-term ('acute') changes in erectile function." Dr Murray and her team say the same thing.

This single-group study could have been stronger in terms of its evidence, said Clint Bahler, MD, from Indiana University in Indianapolis, who was not involved in the study but was asked to comment on the findings.

"They should have followed another group of [healthy] men with elevated PSA who did not get biopsy to compare, for instance," he told Medscape Medical News.

Like Dr Helfand, Dr Bahler pointed out that men who had a benign biopsy (67% of the group) had relatively transient ED, compared with those who had cancer detected.

For the patients who did not get a diagnosis of prostate cancer, median IIEF-5 score was lower only at the 1-week follow-up (P < .001). But for those with prostate cancer detected, the median score was lower at 1 week (P < .001) and at 12 weeks (P = .001) after biopsy.

Notably, there is no detailed breakout of scores for the benign group. "They should give us the scores for the benign group, but these are censored, which is suspicious," said Dr Bahler.

Dr Helfand, Dr Bahler, and the investigators all suspect that longer-term ED might be related to a host of factors, including stress, a diagnosis of cancer, and age.

As Dr Murray's team puts it, "the exact mechanism of this decline in IIEF-5 score for these patients is most likely multifactorial in nature and many factors — including psychogenic causes, fear of results, anxiety related to biopsy, and even anatomical considerations including nerve damage and hematoma — have potential in being related."

At baseline, the average age was 64 years, and ED status was reported as nonexistent by 39% of the men, as mild by 22%, as mild to moderate by 15%, as moderate by 10%, and as severe by 14%.

Age appears to play a role in hw men do in terms of their erections after undergoing prostate biopsy, the investigators report.

For men younger than 60 years, median IIEF-5 score was lower only at the 1-week follow-up (P = .015). But for men 60 years and older, scores were lower at 1 week (P < .001), 4 weeks (P = .024), and 12 weeks (P = .005).

The investigators also used the International Prostate Symptom Score (IPSS) questionnaire to evaluate the men. They focused on data related to lower urinary tract symptoms, and found that there was a significant change at weeks 1 and 4, but not at week 12. In other words, in this cohort of men, symptoms, on average, improved by week 12.

The study authors, Dr Helfand, and Dr Bahler have disclosed no relevant financial relationships.

BJU Int. 2015;116:164, 190-195. Editorial, Abstract

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