A more realistic approach may be to view breast cancer as a two-component disease involving the breast and the body as a whole. Although the primary breast tumor and issues of local control must be managed, the possibility of systemic metastases with their life-threatening consequences should not be overlooked.
Breast cancer can metastasize to any organ, and involvement of bone, lungs, or liver occurs in up to 85% of women who develop distant disease (26,27). In addition to these sites, invasive lobular carcinoma is known to disseminate to the abdominal viscera, uterus, ovaries, and peritoneal surfaces.
Number of cells
Staging After the diagnosis of breast cancer is definitively established, the clinical stage of the disease should be determined. The Columbia Clinical Staging System was used historically but is replaced by the tumor-node-metastases (TNM) system of the American Joint Committee on Cancer (28,29). The TNM system allows both preoperative clinical staging and postoperative pathologic staging to be determined (Tables 40.2 and 40.3).
Table 40.2 Tumor-Node-Metastasis (TNM) System for Staging of Breast Cancer
T4 Tumor of any size with direct extension to chest wall and/or skin (ulceration or skin nodules)
T4a Extension to chest wall, not including only pectoralis muscle adherence/invasion
T4b Ulceration and/or ipsilateral satellite nodules and/or edema (including peau d’orange) of the skin which do not meet the criteria for inﬂammatory carcinoma
NX Regional lymph nodes cannot be assessed (e.g., previously removed)
N1 Metastases to movable ipsilateral level I, II axillary lymph node(s)
N2 Metastases in ipsilateral level I, II axillary lymph node(s) that are clinically fixed or matted, or in clinically detected ipsilateral internal mammary nodes in the absence of clinically evident axillary lymph node metastases
N2a Metastases in ipsilateral level I, II axillary lymph nodes fixed to one another (matted) or to other structures
N2b Metastases only in clinically detected ipsilateral internal mammary nodes and in the absence of clinically evident level I, II axillary lymph node metastases
N3 Metastases in ipsilateral infraclavicular (level III axillary) lymph node(s) with or without level I, II axillary lymph node involvement; or in clinically detected ipsilateral internal mammary lymph nodes and with clinically evident level I, II axillary lymph node metastases; or metastases in ipsilateral supraclavicular lymph node(s) with or without axillary or internal mammary lymph node involvement