A selection algorithm for internal mammary sentinel lymph node biopsy in breast cancer

Internal mammary lymph-node (IMN) metastases in breast carcinomas have a major influence on survival, comparable with the influence of axillary lymph-node metastases (ALNM). Prospective, randomized trials have demonstrated that complete IMN dissection as part of extended radical mastectomy does not improve overall or disease-free survival. In the subset of patients with tumours 1 cm or less in size and no ALNM, information on IMN status would provide important information. In these cases, the presence of IMN metastases would change the staging from stage I to stage IIIB, according to the current tumour, node and metastasis classification. More importantly, it would influence these patientsʹ adjuvant treatment. Lymphatic mapping for sentinel lymph-node (SLN) biopsy has demonstrated extra-axillary drainage in up to 35% of patients. Recent reports have demonstrated the feasibility of internal mammary sentinel lymph-node (IM-SLN) biopsy. Here we review the general prognostic and clinical significance of tumor location and lymph-node metastases in breast cancer and discuss the specific factors associated with IMN identification, metastases and treatment in the pre-SLN and SLN eras. Based on our review, we propose an algorithm for a selective approach to IM-SLN in breast cancer.