Background
Low-dose-rate brachytherapy (LDR-B) is an established treatment for localized prostate cancer. However, while erectile function is relatively well documented, other changes in sexual function are sparsely investigated.

Aim
The study sought to investigate orgasmic dysfunction, urinary incontinence during sexual activity (UIS), changes in penile morphology, and sensory disturbances in the penis following LDR-B.

Methods
A cross-sectional questionnaire-based study in patients who underwent LDR-B at our center from 2010 to 2020. The questionnaire included the International Index of Erectile Function–Erectile Function Domain (IIEF-EF) and questions on orgasm, UIS, changes in penile morphology, and penile sensory disturbances.

Outcomes
Outcomes were prevalence rates of altered perception of orgasm, orgasm associated pain, anejaculation, UIS, alterations in penile morphology, penile sensory disturbances, and predictors of these side effects.

Results
Overall, 178 patients responded to the questionnaire. The median age was 70 years (range, 51-83 years), and the median time since LDR-B was 93 months (range, 21-141 months).

Overall, 142 (80%) were sexually active and 126 (70.8%) had erectile dysfunction (ED). Of the sexually active patients, 8 (5.6%) reported anejaculation and 7 (4.9%) reported anorgasmia. Another 67 (46.9%) had decreased orgasmic intensity, while 69 (49.3%) reported an increased time to orgasm. Twenty-six (18.3%) patients had experienced orgasm-associated pain with a median visual analog pain score of 2. Considering overlap, 44 (31.0%) patients had an unchanged orgasmic function. Six (3.3%) patients had experienced UIS at least a few times. Penile length loss was reported by 45 (25.2%) patients. Seventeen (9.6%) patients reported an altered curvature of their penis and 9 (5%) had experience painful erection. Thirty-three (18.5%) patients had experienced decreased penile sensitivity. On multivariate analyses, ED was the only independent risk factor for altered perception of orgasm (odds ratio [OR], 6.6; P < .0001), orgasmic pain (OR, 5.5; P = .008), and penile shortening (OR, 4.2; P < .0056). No independent risk factors were identified for UIS or sensory penile disturbances.

Clinical implications
Patients undergoing LDR-B should be adequately informed about possible side effects, and clinicians should inquire about these during follow-up visits.

Strength and Limitations
We are the first to comprehensively explore the previously neglected side effects of LDR-B for prostate cancer. Limitations are the cross-sectional design assessing the cohort at different time points following their treatment and the response rate.

Conclusions
Orgasmic dysfunction, changes in penile morphology, and sensory disturbances in the penis are common side effects of LDR-B for prostate cancer. UIS is only experienced by a small minority.