Which patient characteristics drive treatment decisions in elderly patients with early stage hormone receptor–positive breast cancer?

Abstract

538 Background: Hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) is the most common biologic subtype of breast cancer (BC). We examined treatment patterns and outcomes associated with adjuvant or neoadjuvant therapy among elderly patients (pts) in the US. Methods: The analysis included 18,470 first primary HR+HER2- BC pts from the linked SEER-Medicare database. Pts were diagnosed with Stage I-III disease between 1/1/2007-12/31/2011, ≥66 years, continuously enrolled in Medicare Parts A/B in the year prior to diagnosis, enrolled in Part D in the year after diagnosis, and underwent BC surgery ≤6 months after diagnosis. Time-varying Cox proportional hazards regression assessed overall survival adjusting for pt characteristics. Date of last follow-up was 12/31/2013. Results: There were 13,670 (74%) pts treated with hormonal therapy +/- chemotherapy and 4,800 (26%) untreated. Compared to treated pts, untreated pts were older, had earlier stage, lower grade, smaller tumors, poorer performance, higher comorbidity, and less genomic testing for risk of recurrence (p<0.0001). In a multivariate analysis, increasing age, stage, tumor size, tumor grade, comorbidity score and poor performance were significantly associated with higher mortality risks, while use of genomic testing was associated with a lower risk of death. The Cox model showed a 48% higher risk of death in untreated compared to treated pts (HR=1.48; 95% CI=1.35-1.61). Even in a subset of 8,967 pts with stage I disease, tumor size <2.0cm and grade 1/2; untreated pts had a 22% higher risk of death compared to treated pts (HR=1.22; 95% CI=1.05-1.41). Conclusions: Patients who are older with favorable disease characteristics (earlier stage, smaller tumor, lower grade) are less likely to be treated and have a higher risk of death compared to pts who received adjuvant or neoadjuvant therapy. The unmet need among elderly BC pts remains, suggesting that age should not deter guideline-based therapy. [Table: see text]