Radiotherapy to the internal mammary nodes (IMNs) is among the most controversial and polarizing issues in radiation oncology, owing to conflicting data and the need to delineate a balance between potential outcome benefits and cardiopulmonary toxic effects. Though occult IMN involvement is higher in patients with tumors larger than 2 cm, younger women, and patients with axillary metastases, previous randomized clinical trials (RCTs) of mastectomy (without radiation and/or systemic therapies) failed to demonstrate survival benefits with IMN dissection.1 With the recent publication of 2 large RCTs of regional nodal irradiation (RNI) therapy, the status of this debate becomes murkier.