Clinical effect of the pathological axillary assessment method in breast cancer without clinical nodal metastasis.

BACKGROUND This study aimed to assess the clinical effect of the pathological axillary assessment method in breast cancer without clinical lymph node metastasis. METHODS Data of patients with clinically node-negative breast cancer were retrospectively reviewed. The study period was divided into early (January 2000-July 2007) and late (August 2007-December 2014) periods based on the pathological assessment method used (single-sectional and detailed multi-sectional lymph node processing). In the late period, lymph nodes were evaluated at six levels including immunohistochemistry on each 1.5-2 mm interval section. The axillary diagnostic accuracy and role of chemotherapy were assessed. RESULTS In 1698 patients, 27 isolated tumor cells (ITCs), 39 micrometastases, and 205 macrometastases were noted. The sensitivity for pathological N0 diagnosis was dependent on clinical T stage, Tis (97.8%), T1 (83.0%), T2 (74.2%), T3 (54.5%), and T4 (63.6%). ITCs and micrometastases were detected only in the late period, and 84.7% and 91.6% of cases in the early and late period, respectively, did not have macrometastases. The 5-year disease-free interval (DFI) rates were 95.2% in node-negative cases, 98.4% in ITCs/micrometastases, and 91.4% in macrometastases (P < 0.001). In multivariate analysis, the predictor for DFI was estrogen receptor negativity (P = 0.013). Chemotherapy did not improve DFI in patients with node-positive breast cancer. CONCLUSIONS The detailed multi-sectional pathological assessment of axillary lymph nodes detected ITCs and micrometastases. Implementation of chemotherapy should not be based on the minimal nodal metastasis and this type of serially nodal sectioned processing had little clinical significance.