Factors Associated with Endometrial Pathology During Tamoxifen Therapy in Women with Breast Cancer: a Retrospective Analysis of 821 Biopsies

Purpose: This study evaluated the factors associated with endometrial pathologies during tamoxifen use in women with breast cancer.

Methods: This study analyzed 821 endometrial biopsies from women who received tamoxifen for breast cancer. Clinical characteristics were compared according to the presence of endometrial pathology (atypical hyperplasia and cancer). In addition, patients with endometrial polyps were compared with women with normal histology.

Results: Among 821 biopsies, atypical endometrial hyperplasia and cancer were diagnosed in 7 women each. Endometrial polyps were found in 173 women, and 634 women presented normal histology. In comparing women with endometrial pathology (atypical hyperplasia and cancer, n = 14) and those without pathology, parity was significantly lower (P = 0.014) and endometrial thickness was significantly higher (P < 0.001) in women with pathology. In addition, abnormal uterine bleeding was more common in the pathology group (P < 0.001). However, age, body mass index, menopausal status, intrauterine device use, history of diabetes mellitus, and duration of tamoxifen use did not differ according to the presence of pathology. In comparing women with endometrial polyps and those with normal endometrium, significant differences were found in parity (P < 0.001), duration of tamoxifen use (P = 0.003), and endometrial thickness (P < 0.001), but not in the presence of abnormal vaginal bleeding.

Conclusion: Parity, endometrial thickness, and the presence of abnormal vaginal bleeding, but not age, body mass index, and menopausal status, may be associated with endometrial pathology during tamoxifen use in women with breast cancer. This finding might provide useful information for gynecological surveillance and counseling during tamoxifen treatment.