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Bilateral nerve-sparing prostatectomy resulted in better sexual and urinary function outcomes than unilateral or nonnerve sparing surgery, but the difference reached significance only in men who already had high sexual function at baseline, according to the (Comparative Effectiveness Analysis of Surgery and Radiation) study.

The population-based, prospective, observational study reported that bilateral nerve sparing (BNS) surgery was associated with improved recovery of sexual and urinary function 3 years after radical prostatectomy for localized prostate cancer (6.1 points, P=0.004), compared with unilateral nerve-sparing (UNS) surgery and nonnerve-sparing (NNS) surgery, reported Daniel Barocas, MD, of Vanderbilt University Medical Center, in Nashville, and colleagues in .

The changes were assessed using patient-reported sexual and urinary functions on the 26-item Expanded Prostate Index Composite (), with similar changes for both sexual and urinary function in patients with high baseline function (8.23 points, P=0.014) but not in those with low baseline function (4.0 points, P=0.090), the researchers reported.

In a contemporary practice, BNS appeared to have the most benefit in men with high baseline sexual function: "Men with anything less than excellent erectile function [i.e. in the top quartile] to begin with did not have a good outcome," Barocas told 番茄社区app. "That tells us that maybe it's not appropriate to raise the hopes of those men that they will have good function ... it is not worth the incremental risk of positive margin -- although we failed to find one."

In addition, he said, it is important to acknowledge that 44% of the men who underwent surgery did so for low-risk disease, which could have been observed instead.

The findings reflect those of the (Prostate Cancer Outcomes and Satisfaction with Treatment Quality Assessment) study, although the results did not reach significance, and (Cancer of the Prostate Strategic Urologic Research Endeavor) study, which found that statistically significant recovery of erectile function with BNS was limited to men with high baseline sexual function, Barocas et al noted.

Based on a follow-up study of PROSTQA and CaPSURE data, a predictive model was developed that identified patient age, baseline sexual function, and nerve-sparing status as predictors of recovery of erectile function. "We found that these characteristics, as well as comorbidity, predicted response to BNS," Barocas said.

Multivariable analyses found that younger patient age and lower comorbidity were significantly associated with higher 3-year sexual domain scores, while race, D'Amico risk, and the surgeon's volume of surgery were not.

Younger age, non-black racial group, and BNS were associated with better urinary incontinence scores 3 years after BNS surgery versus unilateral or nonnerve-sparing treatment, but as with sexual function, the benefit of BNS was pronounced in men with high baseline sexual function (7.5 points, P=0.015), but did not reach significance in men with low baseline sexual function (2.1 points, P=0.48).

"That nerve sparing was not associated with improved urinary function outcomes in men with low baseline sexual function runs counter to previous studies including CaPSURE," which showed improved urinary function scores with BNS in men in the lowest quartile of baseline sexual function," the researchers noted.

Barocas said that "while this finding is hard to explain ... and further study is needed, currently, the hope to preserve urinary function doesn't seem to justify nerve sparing in men with low sexual function at baseline."

The final analysis of the study included 991 men diagnosed with localized prostate cancer in 2011 to 2012, who had radical prostatectomy as primary treatment, with documented nerve-sparing status and did not have androgen-deprivation therapy.

Overall, 80% of the patients underwent contemporary robotic surgery -- noted by the authors as a research strength -- while 19% and 1% were treated with an open or other approach. The analysis grouped 11 men treated with a UNS procedure and 75 men with NNS surgery, the group noted. The response rate was 98% at 6 months, 96% at 12 months, and 88% at 36 months, and was similar in the two groups.

Study limitations, the authors said, included ascertainment of nerve-sparing status from operative reports and the potential for misclassification, and the limited number of patients who underwent NNS or UNS.

Asked for his perspective, Scott Shelfo, MD, of Cancer Treatment Centers of America in Metro Atlanta, noted the limitations of any observational study, but said the study's conclusions are concepts that many urologists share. "It is notable that there is only an 8.2 sexual function difference between BNS versus UNS/NNS," he told 番茄社区app via email. "This brings into question how much of a role nerves play in the post-op erectile dysfunction process and/or the quality of nerve spare, as roughly 50% of patients with BNS suffer from erectile dysfunction.

"If there is a risk of positive margins with nerve spare, is the risk-to-benefit ratio worth it? In this study, the positive margin rates were similar in the two groups -- 22.35% versus 21.8% -- but this can be highly influenced by the surgeon's clinical judgment regarding to whom he offers nerve sparing based on risk stratification."

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