Impact of adjuvant endocrine therapy in older patients with comorbidities and estrogen receptor-positive, node-negative breast cancer—A National Cancer Database analysis

Background: Data are lacking about the benefit of adjuvant endocrine therapy (ET) in older patients with multiple comorbidities. The authors sought to determine the effect of ET on the survival of older patients who had multiple comorbidities and estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative, pathologic node-negative (pN0) breast cancer. Methods: Women aged ≥70 years in the National Cancer Database (2010-2014) with Charlson/Deyo comorbidity scores of 2 or 3 who had pathologic tumor (pT1)-pT3/pN0, ER-positive/HER2-negative breast cancer were divided into 2 cohorts: adjuvant ET and no ET. Propensity scores were used to match patients based on age, comorbidity score, facility type, pT classification, chemotherapy, surgery, and radiation therapy. A Cox proportional hazards model was used to estimate the effect of ET on overall survival (OS). Results: In the nonmatched cohort (n = 3716), 72.8% of patients received ET (n = 2705), and 27.2% did not (n = 1011). The patients who received ET were younger (mean age, 76 vs 79 years; P <.001) and had higher rates of breast conservation compared with those who did not receive ET (lumpectomy plus radiation: 43.4% vs 23.8%, respectively; P <.001). In the matched cohort (n = 1972), the median OS was higher in the ET group (79.2 vs 67.7 months; P <.0001). In the adjusted analysis, ET was associated with improved survival (hazard ratio, 0.70; 95% CI, 0.59-0.83). Conclusions: In older patients who have pN0, ER-positive/HER2-negative breast cancer with comorbidities, adjuvant ET was associated with improved OS, which may have been overestimated given the confounders inherent in observational studies. To optimize outcomes in these patients, current standard recommendations should be considered stage-for-stage based on life expectancy and the level of tolerance to treatment.