Node-positive breast cancer: Internal mammary node irradiation may benefit patients with mediocentrally located tumors

Key clinical point: Including internal mammary node irradiation (IMNI) with regional node irradiation did not improve disease-free survival (DFS) significantly in the overall cohort of patients with node-positive breast cancer but benefited those with mediocentrally located tumors.

Major finding: The 7-year DFS rate was not significantly different between groups treated without vs with IMNI (81.9% vs 85.3%; hazard ratio [HR], 0.80; 95% CI, 0.57-1.14); however, it was significantly higher in patients with mediocentrally located tumor who were treated with vs without IMNI  (91.8% vs 81.6%; HR, 0.42; 95% CI, 0.22-0.82).

Study details: Findings are from phase 3 KROG 08-06 study including 735 patients with histologically confirmed, node-positive breast cancer who underwent breast-conservation surgery or mastectomy and axillary dissection and were randomly assigned to receive regional nodal irradiation with or without IMNI.

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Disclosures: This work was supported by the Cancer Control of the Ministry of Health, Welfare, and Family Affairs, Korea. The authors declared no conflict of interests.

Source: Kim YB et al. JAMA Oncol. 2021 Oct 25. doi: 10.1001/jamaoncol.2021.6036.