Population-based recurrence rates among older women with HR-positive, HER2-negative early breast cancer: Clinical risk factors, frailty status, and differences by race

Background: Multiple independent risk factors are associated with the prognosis of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer (BC), the most common BC subtype. This study describes U.S. population-based recurrence rates among older, resected women with HR+/HER2- early BC. Methods: We conducted a retrospective cohort study of older women diagnosed with incident, invasive stages I-III HR+/HER2- BC who underwent surgery to remove the primary tumor using the Surveillance, Epidemiology, and End Results (SEER)-Medicare Linked Database (2007–2015). SEER records and administrative health claims data were used to ascertain patient and tumor-specific characteristics, treatment, and frailty status. Cumulative incidences of BC recurrence were estimated using a validated algorithm for administrative claims data. Multivariable Fine-Gray competing risk models estimated adjusted subdistribution hazards ratios and 95 % confidence intervals for associations with BC recurrence risk. Results: Overall, 46,027 women age ≥65 years were included in our analysis. Over a median follow up of 7 years, 6531 women experienced BC recurrence with an estimated 3 and 5-year cumulative incidence rates of 10 % and 16 %, respectively. Higher 3- and 5-year cumulative incidences were observed in women with larger tumor size (5+ cm, 21 % and 28 %), lymph node involvement (4+ nodes, 27 % and 37 %), and with frail health status at diagnosis (13 % and 20 %). Independent of these clinical risk factors, Black, Hispanic and American Indian/Alaskan Native women had significantly increased BC recurrence risks. Conclusions: Rates of recurrence in HR+/HER2- early BC differs by several patient and clinical factors, including high-risk tumor characteristics. Racial differences in BC outcomes deserve continued attention from clinicians and policymakers