Adjuvant endocrine therapy is associated with improved overall survival in elderly hormone receptor-positive breast cancer patients

Purpose There is controversy regarding the survival benefit of endocrine therapy (ET) in elderly patients with early invasive hormone receptor-positive (HR+) breast cancer. In this study, we characterize a single institution’s practice patterns using adjuvant ET for these patients and evaluated the effect of ET on outcomes. Methods A review of a prospectively maintained database identified 483 women ≥ 70 years old who underwent breast -conserving surgery (BCS) for stage I-III HR+ tumors from 2004–2013. We compared clinicopathologic characteristics, overall survival (OS), disease-free survival (DFS), locoregional recurrence (LRR), and breast cancer-specific survival (BCSS) in patients who did and did not receive ET. Results Compared to patients who did not get ET, patients who received ET were younger (median age 76 vs 78 years, p = 0.006), had larger tumors (median size 15 vs 14 mm, p = 0.016), underwent sentinel lymph node (LN) biopsy (83.7 vs 67.8%, p < 0.001), had positive LNs (25.5 vs 9.8%, p = 0.008), and received radiation (XRT, 76 vs 43%, p < 0.001). After adjusting for ASA score, age, LN status, tumor grade, and XRT, receipt of ET was associated with improved OS (HR 0.44; 95% CI 0.25–0.77; p = 0.004) and DFS (HR 0.42; 95% CI 0.28–0.64; p < 0.01). Receipt of ET was associated with improved LRR on univariate analysis (HR 0.25; 95% CI 0.09–0.70; p = 0.008); however, after adjusting for grade and XRT, this was not statistically significant on multivariable analysis (HR 0.38; 95% CI 0.13–1.08; p = 0.069) and was not associated with BCSS (HR 0.59; 95% CI 0.16–2.16; p = 0.43). Conclusions ET was associated with significant improvements in OS and DFS, regardless of clinicopathological features; however, receipt of ET did not impact LRR and BCSS.