The importance of interpectoral nodes in breast cancer.

In a consecutive series of 73 patients undergoing a level III axillary clearance, interpectoral nodes were sought and, if palpable, excised. 18 interpectoral nodes were identified in 15 patients, 10 (14%) of whom had involved and 5 of whom had uninvolved interpectoral nodes. 7 of the 10 patients with involved interpectoral nodes also had axillary node involvement, but 3 patients had positive interpectoral nodes in the absence of involved axillary nodes. A comparison of patient and tumour characteristics in the groups of patients with and without interpectoral node involvement showed that patients who had involved interpectoral nodes were significantly younger and had significantly larger tumours. Interpectoral node involvement by breast cancer is not uncommon and these nodes can be involved in the absence of axillary nodal involvement. They should be looked for, and if identified, excised during axillary clearance.