Clinical Features and Outcomes of Invasive Breast Cancer: Age-Specific Analysis of a Modern Hospital-Based Registry

PURPOSE: We evaluated the clinical features and outcomes of invasive breast cancer (BC) among different age groups by analyzing a modern BC registry including subtypes and treatment information. METHODS: This was a retrospective cohort study of 6,405 women aged 18 years or older with pathologically confirmed stage I, II, or III BC who underwent curative surgery followed by adjuvant therapy at a university-based hospital in Seoul, South Korea, between January 2003 and December 2011. The study end point was all-cause mortality. We used Cox proportional hazards models and hazard ratios (HRs) with 95% CIs calculated after adjusting for age, body mass index, stage, subtype, and treatment, including type of surgery and use of chemotherapy, radiation therapy, hormone therapy, and targeted therapy. RESULTS: During 36,360 person-years of follow-up (median follow-up: 5.45 years; interquartile range, 4.3-7.1), 256 deaths were reported (mortality rate, 7.0/1,000 person-years). The adjusted HR for all-cause mortality was higher in patients older than 40 years (HR, 2.03; 95% CI, 1.44 to 2.87) and older than 60 years (HR, 2.35; 95% CI, 1.63 to 3.39) than in patients aged 40 to 49 years. Across age groups, advanced stage at diagnosis, luminal type as well as triple-negative BC, and not receiving adjuvant treatment were associated with increased risk of mortality. CONCLUSION: A strong J-shaped relationship was observed between age and mortality, indicating worse clinical outcomes in young and old patients. This study suggested a possible benefit of personalized BC screening examination and precise and active treatment strategies to reduce BC-related mortality.