Background. Axillary dissection has been a routine part of breast cancer treatment for more than 100 years. Axillary node involvement is the single most important prognostic variable in patients with breast cancer. Recently, routine node dissection has been eliminated for intraductal carcinoma because so few patients had positive nodes. With the availability of numerous histologic prognosticators and the development of new immunochemical prognostic indicators, it is time to consider eliminating routine node dissection for lesions more advanced than duct carcinoma in situ (DCIS) but with extremely low likelihood of axillary involvement.
Methods. Axillary node positivity, disease-free survival, and breast cancer-specific survival were determined for six breast cancer subgroups by T category: Tis (DCIS), T1a, T1b, T1c, T2, and T3.
Results. Nodal positivity for DCIS was 0%; for T1a lesions, 3%. A large increase in nodal positivity was seen in lesions larger than 5 mm. (T1b, 17%; T1c, 32%; T2, 44%; T3, 60%). The rate of nodal positivity was statistically different as each T category was compared with the next more advanced T category. The disease-free survival and breast cancer-specific survival decreased with every increment in T value.
Conclusions. Axillary node positivity increases as the size of the invasive component increases and is an excellent predictor of DSF and breast cancer-specific survival. Consideration should be given to eliminating axillary node dissection for T1a lesions because of the low yield of positive nodes. Axillary node dissection should be performed routinely for T1b lesions and larger.