Objective: We analyzed tamoxifen use as a malignancy risk factor in women with endometrial polyps.

Methods: This retrospective study included 675 women who underwent hysteroscopic polypectomy in 2010 to 2015 at the University of Campinas. Women were divided into tamoxifen use (n = 169) and no tamoxifen use (n = 506) groups. The primary outcome was endometrial cancer prevalence. Dependent variables included age, parity, years since menopause, presence of abnormal uterine bleeding, endometrial pattern on hysteroscopy, and endometrial thickness.

Results: There were seven cases of endometrial cancer in the tamoxifen use group (4.14%) and 41 in the no tamoxifen use group (8.1%; P = 0.083). On performing multivariate analysis, tamoxifen use was not a risk factor for endometrial cancer (prevalence ratio 0.51, 95% confidence interval [CI] 0.23-1.14, P = 0.101). The no tamoxifen use group had an increased prevalence of malignancy when women presented with abnormal uterine bleeding (prevalence ratio 3.9, 95% CI 2.08-7.29, P < 0.001), age >60 years (prevalence ratio 2.1, 95% CI 1.12-3.93, P = 0.021), or nulliparous status (prevalence ratio 3.13, 95% CI 1.55-6.35, P = 0.002). The tamoxifen use group had increased prevalence of malignancy when women were >60 years (prevalence ratio 7.85, 95% CI 1.05-58.87, P = 0.006) or nulliparous (prevalence ratio 8.36, 95% CI 2.32-30.11, P < 0.001).

Conclusion: Tamoxifen use was not related with a higher prevalence of endometrial cancer in women with endometrial polyps. Abnormal uterine bleeding, age > 60 years, and nulliparous status were associated with malignancy.