Tamoxifen or aromatase inhibitors: which one is the culprit of urinary incontinence in premenopausal breast cancer patients receiving adjuvant hormone therapy?

Aim: The primary aim of this study was to compare tamoxifen versus aromatase inhibitors (AI) in terms of urinary incontinence (UI) in premenopausal female patients receiving adjuvant hormone therapy for breast cancer. A secondary aim was to investigate the prevalence and the affecting factors of UI.

Methods: This study was designed as a multicenter, cross-sectional that included consecutive premenopausal breast cancer patients ≤50 years of age receiving tamoxifen (with/without LHRHa) or AI (with LHRHa) for at least 6 months, between June 2021 and September 2022. Patients with urinary incontinence before hormone treatments and metastatic patients were excluded from the study. Turkish validation of The International Consultation on Incontinence Modular Questionnaire Urinary Incontinence Short Form (ICIQ UI-SF) was used to determine the UI. Using logistic regression methods, we analyzed potential predictive factors for UI.

Results: A total of 206 breast cancer patients were included in this study. A total of 120 (58.2%) patients were receiving tamoxifen plus LHRHa, 40 (19.4%) patients were receiving aromatase inhibitor plus LHRHa, and 46 (22.3%) patients were receiving tamoxifen only. In this study, the prevalence of urinary incontinence was found to be 35.9% (n:74). 41% of the patients receiving tamoxifen and 15.0% of those receiving aromatase inhibitors had complaints of urinary incontinence. There was a statistically significant difference between patients receiving tamoxifen or aromatase inhibitor in terms of urinary incontinence (p=0.001). In the univariate analysis established to predict UI, parity (≥2 vs <2) (OR = 3.23, 95% CI: 1.62-6.46, p= 0.001), tamoxifen (vs AI) (OR = 3.97, 95% CI: 1.58-9.98, p= 0.003), age ( ≥40 vs. <40) (OR = 2.80, 95% CI: 1.37-5.71, p= 0.005), vaginal deliveries (≥2 vs. <2) (OR = 3.28, 95% CI: 1.44-7.46, p= 0.005), hypertension (OR = 3.59, 95% CI: 1.43-9.02, p= 0.007), diuretic use (OR = 2.55, 95% CI: 1.09-5.95, p= 0.031) ), and body mass index (≥25 vs <25) (OR = 1.94, 95% CI: 1.05-3.63), p= 0.034) was found to be predictive. Tamoxifen (OR = 4.71, 95% CI: 1.77-12.56, p= 0.002), hypertension (OR = 3.48, 95% CI: 1.27-9.52, p= 0.015), and age (OR = 2.35, 95% CI: 1.10-5.02, p= 0.027) remained independent predictors for incontinence in multivariate analyses.

Conclusion: We found that tamoxifen had increased the risk of urinary incontinence compared to aromatase inhibitors in patients receiving hormone therapy for breast cancer. In addition, we showed that age and hypertension were also independent predictors for UI. In the context of quality of life, we recommend close follow-up of these patients, as drug adherence may be affected in the event of urinary incontinence.