Kim YB, Byun HK, Kim DY, et al. - In node-positive breast cancer patients, no significantly improved disease-free survival (DFS) was achieved by including internal mammary node irradiation (IMNI) in regional nodal irradiation. However, IMNI may be beneficial for patients with medially or centrally located tumors.

• A multicenter, phase 3 randomized clinical trial of 735 women with node-positive breast cancer who were randomized 1:1 to receive radiotherapy either with IMNI or without IMNI.

• No significant difference in 7-year DFS was observed between patients who received regional nodal irradiation with IMNI vs those who received regional nodal irradiation without IMNI (hazard ratio, 0.80).

• Improvement in 7-year DFS rate by 10% was evident in the IMNI group, in a subgroup analysis of patients with mediocentrally located tumors.

• The incidence of adverse effects did not differ between the 2 treatment groups.