Factors associated with chemotherapy benefit in breast cancer patients with midrange Oncotype DX breast recurrence scores

Chemotherapy for patients with hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, node-negative breast cancer, and with midrange Oncotype DX breast recurrence scores (RS) still needs to be further individualized. To improve the treatment decision making, we aimed to develop a method that provides a single score based on multiple factors associated with chemotherapy benefit. We analyzed Surveillance, Epidemiology, and End Results registry data from 31,731 patients with hormone receptor-positive, HER2-negative, node-negative breast cancer and midrange RS characterized by sociodemographic (age and marital status) and clinicopathologic (tumor size, histologic grade, progesterone receptor status, broad histological classification, lesion laterality, and lesion overlap) features and stratified by RS ranges. For the entire sample and for each characteristic, overall survival was compared between patients who underwent chemotherapy and those who did not (or status unknown) within each RS stratum. There was no any association between chemotherapy and survival for patients with RS = 11-15. However, for patients with RS = 16-25, a chemotherapy benefit was associated with tumor size, histologic grade, progesterone receptor status, histological type, and lesion laterality. In addition, overlapping lesion of breast and married at diagnosis might provide additional predictive information of chemotherapy benefit when RS = 21-25. A simple and effective algorithm was designed by combining these factors to output a novel and personalized chemotherapy benefit score to effectively identify patients with RS = 16-25 who would most likely benefit from chemotherapy, which might facilitate improved treatment by providing individualized recommendations.