Tamoxifen related uterine sarcoma - A retrospective review

Abstract

801 Background: Tamoxifen has been shown to significantly reduce the risk of tumor recurrence in women with receptor-positive breast cancer and has been used for chemoprevention in women with non-invasive cancer and women at high risk of developing breast cancer. One established and accepted risk with this treatment is the increased risk of uterine malignancy. Originally this was felt to be limited to endometrial adenocarcinoma, but recent evidence suggests an increased risk of uterine sarcoma as well. Methods: A 42-year retrospective review was performed at a rural tertiary care center. The charts of all patients with a diagnosis of uterine sarcoma were reviewed. 136 patients with uterine sarcoma were identifed. Any women with a primary diagnosis of breast cancer or use of tamoxifen for adjuvant or preventive therapy were substratified. Results: Of the 136 women with uterine sarcoma, ten patients had primary breast malignancies. Six of these ten women had received a five-year course of tamoxifen prior to the development of uterine sarsoma; four did not receive adjuvant hormonal therapy. Additionally, one of our patients enrolled in the National Surgical Adjuvant Breast and Bowel Project (NSABP) Breast Cancer Prevention Trial developed a malignant mixed mullerian tumor (MMMT) 27 months after completing a five-year course of tamoxifen. Conclusions: We therefore report seven cases of uterine sarcoma occurring subsequent to 60 months of tamoxifen treatment. This is compared to the report of 12 cases identifed from the NSABP treatment and prevention trials secondary malignancy data. We suggest that there may be a higher incidence of uterine sarcoma in tamoxifen-treated patients than that based on the NSABP data. Given the increased risk of uterine malignancy (both adenocarcinoma and sarcoma), as well as other potential complications of tamoxifen use, consideration needs to be taken before beginning hormonal therapy, especially in a prevention setting. No significant financial relationships to disclose.