Abstract
BACKGROUND: Metaplastic breast carcinoma (MpBC) is a rare histological subtype of breast cancer, and its prognosis is relatively poor. The survival trend of MpBC with different hormone receptor statuses has remained unclear over the past two decades. METHODS: MpBC patient data were collected from the Surveillance, Epidemiology, and End Results database from 2000 to 2019. Patients were divided into two groups according to their hormone receptor status (negative and positive). The survival probabilities were calculated via Kaplan‒Meier curves. Logistic regression analysis was used to obtain odds ratios for treatment and demographic characteristics. Multivariate Cox regression was used to identify prognostic factors. RESULTS: A total of 3,076 patients were enrolled, and a significant improvement in survival was observed over the last 10 years. For HR-negative MpBC patients, both overall survival and breast cancer-specific survival improved, whereas no survival improvement was observed for HR-positive patients. Compared with those in the time period from 2000 to 2009, the proportion of negative nodes and the likelihood of receiving chemotherapy increased for HR-negative patients from 2010 to 2019. In the HR-negative subgroup, the survival of Whites improved significantly, whereas the survival of Blacks improved in the HR-positive subgroup. CONCLUSIONS: The survival of HR-negative MpBC patients has improved significantly in the past 20 years, which may be related to early diagnosis, increased adjuvant therapy and medical development, but no trend towards improvement has been observed in HR-positive patients. Racial disparities in different HR statuses also need to be addressed.