Survival Comparison Between Adjuvant and Neoadjuvant Radiotherapy for Non-inflammatory Non-metastatic Breast Cancer

Objective: To compare the survival benefit between neoadjuvant and adjuvant radiotherapy for non-inflammatory non-metastatic breast cancer patients.Method: We conducted a retrospective cohort study using surveillance, epidemiology and end results databases. Our study recruited patients who had been diagnosed with stage I-III breast cancer and underwent surgery and radiotherapy. The overall survival was calculated by Kaplan Meier method. Cox risk model was used to determine the impact of radiotherapy according to stage, molecular subtype and other risk factors. Propensity score matching was used to balance measurable confounding factors. Results: Of all the 411483 enrolled patients varying from 1975 to 2016, 1712 patients received neoadjuvant radiotherapy, and 409567 patients received adjuvant radiotherapy. Compared with the adjuvant radiotherapy group, the neoadjuvant radiotherapy group showed significantly higher risks of overall mortality and breast cancer-specific mortality. Survival differences in treatment sequences were correlated with stage, molecular subtypes and other risk factors.Conclusion: According to the results of this study, neoadjuvant radiotherapy did not show a survival advantage, and adjuvant radiotherapy is still the primary treatment. However, neoadjuvant radiotherapy also has some theoretical advantages, such as phase reduction and recurrence reduction. Therefore, it is still worthy of further exploration.