ABSTRACT
Objective To analyze the clinicopathological features and prognostic characteristics of breast cancer (BC) patients with a history of endometrial cancer (EMC). Methods A thousand three hundred and twenty-four BC patients with a history of EMC were analyzed retrospectively. Patients with primary BC were matched as controls according to the distribution of year of diagnosis. The clinicopathological features and tumor-specific survival were compared including the age of diagnosis, the affected side, type of pathology, histological degree of differentiation, hormone receptor status, lymph node metastasis and clinical staging. Results The incidence of BC in patients with EMC was 1.69%, which was 4-8 times that of the general population. Compared with primary BC, secondary BC had a higher diagnostic age of more than 60 years and a lower proportion of lymph node metastasis. There were no significant differences in the affected side, pathological type, differentiation degree, hormone receptor status and clinical stage between the two groups. The history of EMC is an independent protective factor for BC (HR=0.653, P=0.002). For patients with positive hormone receptors, secondary BC patients showed better survival than primary BC patients (P=0.0001), while for hormone receptor negative patients, there was no significant difference in BC-specific survival between the two groups (P=0.329). Conclusions The increased morbidity of BC in EMC patients may be associated with a common hormone-dependent and similar susceptibility genes. The history of EMC may have protective effect for hormone receptor-positive BC patients.