Tamoxifen associated uterine pathology in breast cancer patients with abnormal bleeding

The purpose of this study was to evaluate the underlying pathology in breast cancer patients treated with tamoxifen who present with abnormal bleeding. A total of 56 cases were studied and the histopathologic features of 50 curettage and 18 laparotomy specimens were reviewed. All patients were under tamoxifen treatment (10-40 mg daily) for a period ranging from 5 months to 15 years. Cervical and endometrial polyps were the most common finding in the D and C material (44%). Hyperplasia was the most frequent feature identified at hysterectomy, often combined with leiomyomas, adenomyosis and ovarian tumors. Five primary adenocarcinomas of the endometrium, most of them Stage I beta, Grade I minimally invading, were found as well. These data support the hypothesis that tamoxifen exerts a proliferative estrogen-like effect on the uterus. Abnormal bleeding in women under TAM treatment warrants prompt investigation and careful follow up of the patients.