Effect of adjuvant tamoxifen on the endometrium in women with breast cancer: a prospective study using office endometrial biopsy.

Abstract

To determine the frequency of developing abnormal pathologic changes in the endometria of tamoxifen-treated women. To characterize the type of pathologic changes involved. Between October 1991 and September 1998, 159 patients initiating tamoxifen therapy for breast cancer confined to the breast and axillary lymph nodes were entered in a prospective study. In this study, office endometrial biopsies (EMBs) were obtained during the initiation of tamoxifen and at 6-month intervals for a 2-year period. Three subsequent annual EMBs were recorded for each patient, amounting to a 5-year surveillance. One hundred fifty-nine patients with a median age of 50 years were entered onto study. Patients were assessable if EMBs were performed at least 1 year after the initiation of tamoxifen treatment. Nine patients (5. 7%) were considered protocol violations. The remaining 111 assessable patients underwent a total of 635 EMBs (mean, 5.8 EMBs), with a median surveillance time of 36 months. Eighty-two (12.9%) of the 635 biopsies revealed tissue insufficient for diagnosis. Fourteen patients (12.6%) underwent dilation and curettage (D&C) for an abnormal EMB, persistent bleeding, or for evaluation of adnexal masses at the time of laparoscopy. Findings at D&C included complex hyperplasia (n = 1), abnormal histiocytes (n = 1), simple hyperplasia (n = 2), polyps (n = 4), endocervical polyp (n = 1), and decidualization (n = 2). Three D&Cs were negative. Three patients have undergone hysterectomy. EMB was used to monitor the endometrium in the majority (95%) of breast cancer patients on tamoxifen in this trial, but the utility of routine EMB for screening in tamoxifen-treated women seems limited.