Revision of breast cancer staging: the 6th edition of the TNM Classification.

A Breast Task Force comprised of nationally known experts in the field of breast cancer treatment was charged with recommending additions and changes for the 6th edition of the TNM Classification that were based on published evidence and/or were consistent with widespread clinical consensus. Additions made to the staging system were designed to facilitate the uniform collection of clinically relevant information about new techniques for the detection of metastatic cells. These additions include quantitative criteria to distinguish micrometastases from isolated tumor cells, and specific identifiers to record the use of sentinel lymph node biopsy, immunohistochemical (IHC) staining, and molecular biology techniques. Revisions of the previous staging system are related to the number of affected axillary lymph nodes and to the classification of level III axillary lymph nodes and lymph nodes outside of the axilla.