Synchronous Double Cancer Developing in the Uterine Cervix and Endometrium of a Patient Taking Tamoxifen after Surgery for Breast Cancer

Aim: Tamoxifen (TAM) is known to be a risk factor for endometrial cancer, and it is also reported to be a risk factor for cervical cancer. Case: As reported here, endometrial cancer and adenocarcinoma of the cervix developed during the second year that a patient was taking TAM after surgery for breast cancer. Endometrial cancer was a stage IA well-differentiated endometrioid adenocarcinoma, and cancer of the cervix was a stage IB1 cervical adenocarcinoma. Breast cancer has not recurred for 2 years since surgery. TAM resulted in synchronous double cancer in the form of endometrial cancer and adenocarcinoma of the cervix. Including the patient’s original breast cancer, the patient had metachronous triple cancer. Conclusion: Lesions of the cervix and endometrium must not be overlooked while a patient is taking TAM.