Trends in Locoregional Therapy in Older Women with Early-Stage Hormone Receptor-Positive Breast Cancer by Frailty and Life Expectancy

Background: In women ≥ 70 years of age with T1N0 hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer, breast surgery type and omission of axillary surgery or radiation therapy (RT) do not impact overall survival. Although frailty and life expectancy ideally factor into therapy decisions, their impact on therapy receipt is unclear. We sought to identify trends in and factors associated with locoregional therapy type by frailty and life expectancy.

Methods: Women ≥ 70 years of age with T1N0 HR+/HER2- breast cancer diagnosed in the Surveillance, Epidemiology, and End Results (SEER)-Medicare database between 2010 and 2015 were stratified by validated claims-based frailty and life expectancy measures. Therapy trends over time by regimen intensity ('high intensity': lumpectomy + axillary surgery + RT, or mastectomy + axillary surgery; 'moderate intensity': lumpectomy + RT, lumpectomy + axillary surgery, or mastectomy only; or 'low intensity': lumpectomy only) were analyzed. Factors associated with therapy type were identified using generalized linear mixed models.

Results: Of 16,188 women, 21.8% were frail, 22.2% had a life expectancy < 5 years, and only 12.3% fulfilled both criteria. In frail women with a life expectancy < 5 years, high-intensity regimens decreased significantly (48.8-31.2%; p < 0.001) over the study period, although in 2015, 30% still received a high-intensity regimen. In adjusted analyses, frailty and life expectancy < 5 years were not associated with breast surgery type but were associated with a lower likelihood of axillary surgery (frailty: odds ratio [OR] 0.86, 95% confidence interval [CI] 0.76-0.96; life expectancy < 5 years: OR 0.22, 95% CI 0.20-0.25). Life expectancy < 5 years was also associated with a lower likelihood of RT receipt in breast-conserving surgery patients (OR 0.30, 95% CI 0.27-0.34).

Conclusions: Rates of high-intensity therapy are decreasing but overtreatment persists in this population. Continued efforts aimed at appropriate de-escalation of locoregional therapy are needed.