Contouring Guidelines for the Axillary Lymph Nodes for the Delivery of Radiation Therapy in Breast Cancer: Evaluation of the RTOG Breast Cancer Atlas

To cover 95% of lymph nodes at the cranial and anterior borders of level I, an additional clinical target volume margin of 3.78 cm and 3.11 cm, respectively, is necessary. The RTOG guidelines may be insufficient for coverage of axillary disease in patients with clinical nodal involvement who are undergoing neoadjuvant chemotherapy, incomplete axillary dissection, or treatment with intensity modulated radiation therapy. In patients with pretreatment diagnostic CT chest scans, fusion with simulation CT should be considered for tumor delineation.