Partial Breast Irradiation Without Sentinel Lymph Node Biopsy in Low-Risk Early Breast Cancer

This is a multicenter, randomized, phase III non-inferiority trial in women aged 40 years or older with clinically node-negative (cN0), pathologically pT1 (≤2 cm), grade 1-2, lymphovascular invasion (LVI)-negative invasive breast cancer treated with breast-conserving surgery (BCS) in whom sentinel lymph node biopsy (SLNB) was omitted (pNx). Eligible patients are randomized 1:1 to partial breast irradiation (PBI) or whole breast irradiation (WBI). The primary aim is to determine whether PBI is non-inferior to WBI with respect to the 5-year recurrence-free survival (RFS) rate. Secondary aims include comparison of axillary recurrence, overall survival, locoregional recurrence, treatment-related toxicity, and quality of life between arms.

NCT Number	NCT07757958
Lead Sponsor	Samsung Medical Center Collaborators: National Institute of Health, Korea
Conditions	Breast Cancer, Node-negative Breast Cancer, Early-Stage Invasive Breast Carcinoma
Enrollment	520 participants
Start Date	2026-08-01
Primary Completion	2036-06 (estimated)
Study Completion	2036-06 (estimated)
Updated on ClinicalTrials.gov	2026-08-11