Response-Adapted Omission of Nodal Boost In N3 Breast Cancer After Neoadjuvant Therapy

This is an open‐label, multicenter, randomized phase 3 trial. Eligible patients are womenwith cN3 breast cancer who have completed neoadjuvant systemic therapy (NST), undergonebreast/axillary surgery with the internal mammary, supraclavicular, and infraclavicularnodes left undissected, and have no macroscopic residual disease in these stations onpost‐NAT [¹⁸F]FDG PET‐CT or other imagings. The primary endpoint is 3‐year invasivebreast cancer recurrence‐free interval (IBCRFI). Secondary endpoints include locoregionalrecurrence‐free survival, distant metastasis‐free survival, disease‐free survival,overall survival, toxicity, and patient reported outcomes. This trial will providehigh‐level evidence on the safety of nodal boost omission in cN3 breast cancer patientswith clinical complete response after NST. If non‐inferiority is confirmed, this strategycould establish a new, toxicity‐sparing standard for regional nodal irradiation in thishigh‐risk population.