[Internal mammary lymph node invasion in breast cancer: myth or reality?].

The internal mammary nodes are often underestimated as breast cancer lymphatic pathway spread. It is yet the first site of lymphatic invasion in central or internal tumors and the second site in external tumors. The intra-thoracic situation of internal mammary nodes explains partly, the difficulty of its exploration. To evaluate the risk of internal mammary node invasion, some predictive factors are established (tumor size, internal or central tumor location, axillary node invasion and young age). Prognostic and therapeutic impact of invasion justifies its systematic research. Without exploring internal mammary nodes status, TNM classification remains, incomplete. CT scanner, magnetic resonnance imaging, positron emission tomography scanner and sentinel node exploration technique are helpful to explore this region and to adapt its irradiation.