Omission of postmastectomy radiotherapy for patients with clinically node-positive breast cancer downstaged to ypN0 after neoadjuvant chemotherapy

The significance of postmastectomy radiotherapy (PMRT) in breast cancer patients who initially have clinically node-positive disease but achieve downstaging to ypN0 following neoadjuvant chemotherapy (NACT) is uncertain. A retrospective study at Sichuan University (China) investigated outcomes of such patients who did or did not receive PMRT. There were no significant differences between the two groups for the 5-years rates of locoregional recurrence-free survival, distant metastasis-free survival, breast cancer-specific survival, and overall survival. In multivariate analysis, PMRT was not a significant risk factor for any of the endpoints. The authors conclude that among patients with cN+ breast cancer who turn ypN0 after neoadjuvant chemotherapy, omission of postmastectomy radiotherapy was oncologically safe.