Breast cancer in women aged 80 years and older: Clinical characteristics and treatment patterns according to biologic subtype.
e12594 Background: Older age is associated with poorer breast cancer-specific survival (BCSS) outcomes, despite a higher prevalence of biologically favorable disease. We sought to evaluate differences in the clinical characteristics and management of older women according to biologic subtype of breast cancer. Methods: The Surveillance, Epidemiology, and End Results (SEER) treatment database was queried to identify all women aged 80 years or older with a first diagnosis of invasive breast cancer between 2010 and 2016. Patients were subgrouped according to biologic subtype and clinical and treatment-related variables were compared. Multivariable logistic regression was then performed to determine factors independently associated with receipt of breast-conserving surgery (BCS) and adjuvant radiation. Results: Overall, 27,375 women with a median age of 84 (range, 80-108 years) met inclusion criteria. The majority of older women were diagnosed with HR+HER2- breast cancer (78.9%), followed by HER2+ (11.0%) and triple-negative breast cancer (TNBC) (10.0%). In women with stage I-III disease, non-operative management was employed in 13.4% of HR+HER2- patients, compared to 16.7% of HER2+ patients and 11.0% of TNBC (p < 0.001). In those undergoing surgery, BCS was most common in HR+HER2- patients (80.9%), compared to HER2+ (68.9%) and TNBC (67.8%; p < 0.001). Axillary surgery was performed in 74.0% of early stage patients with HR+HER2- disease, compared to patients with HER2+ (77.8%) and TNBC (79.3%; p < 0.001). In adjusted analyses controlling for stage and clinical variables, women aged 80 years or older with HER2+ breast cancer and TNBC had a lower likelihood of BCS (ORHER2+ 0.72, 95% CI 0.65-0.80; ORTNBC 0.72, 95% CI 0.65-0.81), and an increased likelihood of adjuvant radiation (ORHER2+ 1.14, 95% CI 1.02-1.27; ORTNBC 1.40, 95% CI 1.25-1.57). Conclusions: One fifth of women with breast cancer over age 80 are diagnosed with HER2+ and triple-negative subtypes, which are associated with more aggressive local therapy. Further studies are warranted to determine if higher rates of adjuvant radiation optimize local control in older HER2+ and TNBC patients at increased risk for early locoregional recurrences.