Radiotherapy to the chest wall and regional lymph nodes (under the arm, above the collar bone and under the breast bone), known as regional
nodal irradiation, is used after mastectomy in women with node - positive breast cancer who are treated with adjuvant systemic therapy.
Mignano, J.E., Zahurak, M.L., Chakravarthy, A., Piantadosi, S., Dooley, W.C., Gage, I. Significance of axillary
nodal extranodal soft tissue extension and indications for post-mastectomy
irradiation.