Capturing breast cancer subtypes in cancer registries: Insights into real-world incidence and survival

Breast cancer treatment is guided by diagnostic subtyping, yet cancer registries do not routinely capture this information, and real-world studies reporting subtype-specific incidence and survival do not reflect contemporary clinical management. We analysed breast cancer incidence and survival using Queensland cancer registry data (2017-2019), stratifying by hormone receptor (HR) and HER2 status. Subtype-specific, age-standardised incidence rates were: 125.6 HR+/HER2- cases/100,000 women (76.0% of all diagnoses), followed by 17.7/100,000 for triple-negative (TNBC; 10.3%), 15.0/100,000 for HR+/HER2+ (8.7%), and 8.6/100,000 for HR-/HER2+ (5.0%). Compared to HR+/HER2-, all other subtypes had poorer breast cancer-specific survival (BCSS) and overall survival (OS; except HR+/HER2+ for OS) at 2-years, with OS associations attenuated but still significant for TNBC at 4-years. Stratifying by stage at diagnosis, TNBC had consistently poorer 2-year BCSS in those with stage I-III TNBC (HR adj >7), and marginally poorer in those with stage IV. HR+/HER2- breast cancer is the most common subtype and has the best short-term prognosis. TNBC has markedly poorer short-term survival, even when diagnosed at an early stage. This study provides real-world data for benchmarking breast cancer incidence and survival, and highlights the importance of capturing receptor status and stage for cancer surveillance. Routinely capturing breast cancer subtypes and stages in cancer registries needs to be prioritised to assess the real-world efficacy of evolving targeted therapies and to inform tailored surveillance for high-risk subtypes. • TNBC had the poorest 2- and 4-year survival, even in those with early-stage disease • Survival in HER2+ breast cancer subtypes continues to improve • Capturing subtypes and stages in cancer registries is critical for surveillance