In this section we highlight a few of the international consensus guidelines on the use of imaging in staging assessment of breast cancer (BC). The role of imaging in the screening of breast cancer is an entirely different subject and beyond the scope of current discussion.
Based on the 7th edition of the American Joint Committee on Cancer (AJCC), BC is staged according to the TNM classification, as with other common solid adult tumors. The T-stage (primary tumor) is dependent on tumor size, invasion of chest wall (importantly, deep to the pectoralis muscles) and skin, and presence of an inflammatory component. The N-stage (nodal) is determined by the presence and numbers of involved nodes based on location; involvement of supraclavicular, infraclavicular, and internal mammary lymph nodes confer a higher nodal stage than do axillary lymph nodes, in that order. Presence of microscopic foci of tumor cells in circulating blood, bone marrow, or nonregional nodal tissue in asymptomatic patients constitutes M0 (i+) disease, while macroscopic deposits in distant organs constitutes M1 disease.
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