Uterine sarcomas in breast cancer patients treated with tamoxifen

Tamoxifen (TMX) has been related with the development of uterine sarcomas. Since the first reported case in 1988, 65 TMX-related cases have been referred to. Here we present three new cases of uterine sarcomas in patients with breast cancer treated with TMX and we comment on the outcome of the cases described in the literature. In the past 25 years, 60 uterine sarcomas have been diagnosed and treated in Hospital Clínic. Three patients have previously received TMX 20 mg/day for 3, 5, and 7 years for breast cancer. Uterine sarcoma appeared 5, 5, and 7 years, respectively, after the start of TMX treatment, and all of them had stage I (FIGO) disease. Two patients had a carcinosarcoma and one patient had an adenosarcoma. After treatment, the disease progressed in two patients and the third patient is alive having a follow-up of 42 months. The low incidence of uterine sarcomas makes it difficult to establish a relationship with TMX. Nevertheless, looking at the literature data, 20 mg/day of TMX over 1 year could be enough to develop uterine sarcoma; the sarcoma appears mainly during the first 8 years and seem to behave more aggressively. Although only 65 cases have been reported in the past 14 years, a strict follow-up is necessary in patients with breast cancer receiving TMX therapy.