Radiotherapy Utilization for Patients Over Age 60 With Early Stage Breast Cancer.

ABSTRACT

INTRODUCTION: Recent studies have questioned the relative benefit of radiotherapy (RT) for older patients with favorable breast cancer given the lack of survival benefit and marginal local control benefit. Despite the 2004 National Comprehensive Cancer Network (NCCN) guidelines advocating for the option of hormonal therapy alone, trends in utilization rates of RT in this group are not well-documented. We analyzed our institutional experience with implementation of the guidelines over time. MATERIAL AND METHODS: We identified 564 patients aged ≥ 60 years with favorable breast cancer treated with breast conserving surgery from 2000 to 2017. Patients met criteria for Cancer and Leukemia Group B (CALGB) 9343, Postoperative Radiotherapy in Minimum Risk Elderly (PRIME II), or the very-low risk cohort identified in the Toronto-British Columbia study. Multivariable logistic regression analysis was performed to assess the magnitude of association between omission status, grade, and tumor size while controlling for age and year of diagnosis. RESULTS: Overall RT omission rates were 17.6% prior to the 2004 NCCN update and 45% after the publication of the 10-year CALGB data in 2013. The overall RT omission rate was 29%. Patients with grade 1 to 2 histology (odds ratio, 3.2; 95% confidence interval, 1.3-7.7; P = .01) and tumors < 1 cm (odds ratio, 1.60; 95% confidence interval, 0.4-0.9; P = .007) were more likely to omit RT than those with higher grade or larger tumors. CONCLUSIONS: We observed a slight decrease in the use of RT over time, suggesting a move towards adoption of the NCCN guidelines. There remains a fundamental need to continue to individualize breast cancer care based on risk stratification and make evidenced-based treatment recommendations with equitable use of health care resources.