Florid polypoid endometriosis exacerbated by tamoxifen therapy in breast cancer

We report an unusual case where tamoxifen may have exacerbated the growth of multiple polypoid endometriotic implants.

A premenopausal woman with right breast intraductal carcinoma underwent modified radical mastectomy and received six courses of chemotherapy, followed by continuous oral tamoxifen. Irregular vaginal bleeding was noted 5 years after the mastectomy and transvaginal ultrasound detected a 6-cm cul-de-sac mass. The serum CA 125 level was 138.86 U/mL. Surgical pathology showed florid polypoid endometriosis over the resected rectal segment and endometriotic implants over multiple biopsy sites of the peritoneal surface.

The estrogenic effects of tamoxifen may have induced florid endometriosis in this hypoestrogenic woman. If breast cancer patients have preexisting endometriosis, adjuvant hormonal therapy other than tamoxifen should be considered.