Prognosis of Metaplastic Breast Cancer: A Population‐Based Matched Cohort Study

PURPOSE: Metaplastic breast cancer (metBC) is a rare subtype of breast cancer known for its challenging management. The impact of this histological subtype on prognosis remains unclear. METHODS: Data were collected from the Swedish Cancer Registry between 2008 and 2018. Patients with metBC were matched 2:1 with breast cancer cases of no special type (NST). Survival outcomes were analyzed using cause-specific hazard models for breast cancer specific survival (BCSS) and Cox proportional-hazards models for overall survival (OS). RESULTS: In total, 127 metBC patients were matched 2:1 with 245 NST patients, with a median follow-up period of 54 months. When adjusted for matching variables and treatment-related characteristics, metBC was not significantly associated with either BCSS (cause-specific Hazard Ratio (HR): 1.13; 95% Confidence Interval (CI): 0.66-1.92) or OS (HR: 1.23; 95% CI: 0.83-1.82). CONCLUSION: With appropriate treatment, metBC may have survival outcomes comparable to NST. Larger studies with longer follow-up are needed to provide further insights.