Prevalence of occult metastases in axillary sentinel lymph nodes of breast carcinoma.

Recently, sentinel lymph node biopsy (SLNB) has been accepted as a standard method of assessment of axillary lymph nodes in breast cancer patients with no clinical lymphadenopathy. There is no standard pathologic method to evaluate sentinel lymph nodes. The purpose of this study is to evaluate the frequency of occult lymph node metastasis in sentinel lymph nodes via serial sectioning and immunohistochemical study with cytokeratin and its relationship with other clinicopathologic factors. Paraffin-embedded blocks of axillary sentinel lymph nodes of breast cancer patients, biopsied in 2005-2009 and reported as negative, were reviewed with 3 µm sections, H and E staining and immunohistochemical study with an epithelial cytokeratin marker. Clinicopathologic data and relapse, if occurred was recorded and its relationship with occult metastasis was statistically analyzed. Sixty-eight sentinel pathology blocks of 66 patients (65 women and one man, median age 49 years) were investigated. Four cases (5.8%) of occult metastases were found, one by HE staining, and three cases with IHC (1 micrometastasis, 2 isolated tumor cells). Accuracy of reported cases was 94.1% upon re-examination. Sixty-four patients were followed after surgery and adjuvant therapy (range: 6-38 months, median: 21 months). No relapse was reported. There was no significant statistical relationship between occult metastasis and disease-free survival. Although 4 cases (5.8%) of sentinel lymph nodes were positive in the complementary study, with a median follow-up of 21 months, we found no difference in disease-free survival between these patients and others. To show a significant, however small, difference, one needs further research with a greater number of patients and longer follow-up.