The Impact of Surgeon Referral and a Radiation Oncologist Productivity-Based Metric on Radiotherapy Receipt Among Elderly Women with Early-Stage Breast Cancer: Analysis from a Tertiary Cancer Network

Abstract Purpose: Guidelines for early-stage breast cancer allow for radiotherapy (RT) omission following breast conserving surgery (BCS) among older women, though high utilization of RT persists. This study explores surgeon referral and the effect of a productivity-based bonus metric for radiation oncologists in an academic institution with centralized quality assurance (QA) review.Methods: We evaluated patients >70 years of age treated with BCS for ER+ pT1N0 breast cancer at a single tertiary cancer network between 2015-2018. The primary outcomes were radiation oncology referral and RT receipt. Covariables included patient and physician characteristics, and treatment decisions before versus after productivity metric implementation. Univariable generalized linear effects models explored associations between these outcomes and covariables. Results: Of 703 patients included, 483 (69%) were referred to radiation oncology and 273 (39%) received RT (among those referred, 57% received RT). No difference in RT receipt pre- versus post- productivity metric implementation was observed (p=0.57). RT receipt was associated with younger patient age (70-74 years, OR 2.66, 95% CI 1.54-4.57) and higher grade (grade 3, OR 7.75, 95% CI 3.33-18.07). Initial referral was associated with younger age (70-74, OR 5.64, 95% CI 3.37-0.45) and higher performance status (KPS ³90, OR 5.34, 95% CI 2.63-10.83). Conclusion: Non-referral to radiation oncology accounted for half of RT omission, but was based on age and KPS, in accordance with guidelines. Lack of radiation oncologist practice change in response to misaligned financial incentives is reassuring, potentially reflecting centralized QA review. Multi-institutional studies are needed to confirm these findings.