Treatment Patterns by Physiologic Age in Older Adults with Early-Stage Breast Cancer: A Single Institution Retrospective Study

<b>Background/Objectives</b>: Older adults with breast cancer may suffer from over- and undertreatment if intensity of therapy does not align with their physiologic age. We sought to evaluate the association between physiologic age, chronologic age, and treatment patterns in women ≥ 70 years with non-metastatic breast cancer. <b>Methods</b>: Patients ≥ 70 diagnosed with non-metastatic breast cancer 10/2021-3/2024 who had received surgical therapy and frailty (Geriatric-8) and life expectancy (Schonberg index) screening at our institution were identified from our institutional database. Descriptive analyses were run using chi-square tests of proportion. In the largest subgroup (patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2)-disease), multivariate logistic regression adjusting for patient- and disease-level characteristics was used to assess the relationship between life expectancy < 10 years and the omission of sentinel lymph node biopsy (SLNB) and radiation therapy (RT). <b>Results</b>: Of 272 patients, 104 (38.2%) screened positive for frailty and 64 (23.5%) had a life expectancy of <10 years. On bivariate analysis, a higher proportion of frail patients (44 (42.3%) had a life expectancy < 10 years, while 20 (11.9%) robust patients had a life expectancy < 10 years (<i>p</i> < 0.001). Most patients (226, 83.1%) had HR+/HER-2 negative disease; 10 (3.7%) had HER2+ disease; and 33 (12.1%) had triple-negative breast cancer (TNBC) (<i>p</i> < 0.001). Life expectancy was not significantly associated with omission of SLNB (life expectancy < 10 years: reference; life expectancy ≥ 10 years: OR 0.81 95% CI [0.20-3.28]) or RT (life expectancy < 10 years: reference; life expectancy ≥ 10 years: OR 1.14, 95% CI 0.44-2.93]) in patients with stage I-II HR+/HER-2- disease on adjusted analysis. <b>Conclusions</b>: While patients at risk for frailty and limited life expectancy are relatively common in our population, these measures may not significantly influence patient and clinician treatment decision making. Future efforts to tailor therapy by measures of physiologic age are needed.