Endometrial cancer after tamoxifen treatment: a descriptive study of 25 breast cancer patients who subsequently developed endometrial cancer.

The aim of this study was to determine whether tamoxifen affects the histopathological features and clinical outcome of endometrial cancer occurring after breast cancer. 25 patients with a history of breast cancer who subsequently developed endometrial cancer were identified by computer assisted linkage of the Lainz Medical Center Tumor Registry with the National Austrian Cancer Registry. 8 endometrial cancers were tamoxifen-associated, whereas 17 cases were not. The median time of tamoxifen use was 32 months, with a median cumulative tamoxifen dose of 27 g. Detailed histopathological data did not show substantial difference between the two groups. The distribution by stage (FIGO) in the tamoxifen group was Stage I, 7 (87.5) with 1 patient unstaged (12.5%); and Stage I, 13 (76%), II, 2 (12%) and, stage III 2 (12%) for the non-tamoxifen users. No risk of high-grade endometrial lesions with a poor prognosis was found. The only suggestion of a difference was a trend for the mean interval between detection of breast and endometrial cancer to be shorter in the tamoxifen group (50.5 vs. 88.1 months p = 0.07). The conclusion to be drawn from this study appears to be that endometrial cancers occurring after tamoxifen exposure are of the same tumor type. Due to the small number of cases described we were not able to disprove the hypothesis that tamoxifen associated tumors were different in terms of clinical outcome and survival. Regular gynecological examinations are recommended for all breast cancer patients.