Ten-year survival of women with invasive breast cancer by stage, molecular subtype, and grade combined: a population-based study.

BACKGROUND: Stage at diagnosis, histologic grade, and molecular subtypes are established prognostic indicators for women with breast cancer (BC), but their impact on population-based survival estimates is poorly documented. This study assessed long-term BC survival trends according to these factors. METHODS: We identified women aged <75 years diagnosed with stage I-IV invasive BC between 2004 and 2014 from the Friuli Venezia Giulia (North Eastern Italy) Cancer Registry (N = 10,476). Follow-up through 2023 was used to estimate overall and net survival (NS) according to combinations of prognostic factors. RESULTS: The highest 10-year NS (10-NS) was observed in women with stage I HR+/HER2- subtype (98.8%), while it was 35.1% for stage III triple-negative (TN) subtype. Among women with stage IV BC, 10-NS was 18.9% for those HR-/HER2+, 11.5% for those HR+/HER2+, 8.3% for HR+/HER2-, and 6.7% for TN. For each stage, NS decreased with increasing grade. Comparing period of diagnosis (2004-2009 vs 2010-2014), 10-NS remained >90% for women with stage I BC, but improved for stage III and aggressive subtypes (HR-/HER2+ and TN). In women with stage III HR-/HER2+ BC, 10-NS increased from 48.6% to 87.9% (+39 percentage points), while when diagnosis was stage III TN BC it rose from 28.8% to 42.3. CONCLUSION: Population-based estimates of long-term BC survival by combined stage, grade, and molecular subtype can inform the interpretation of evolving therapeutic strategies and improve risk stratification for patient follow-up.