OBJECTIVETo investigate an optimal examination method to detect micrometastases in sentinel lymph nodes (SLNs) of breast cancer.

METHODSFirstly, the SLNs of breast cancer were found by 99mTc-DX isotope method. Secondly, all the SLNs which were negative by routine HE examination were serially sectioned at a 100 microm interval and stained by both HE and immunohistochemistry for detecting micrometastases. All tumor tissue paraffin blocks were also sectioned and stained with HE and immunohistochemistry as control.

RESULTSTotally, 121 SLNs and 44 tumors of 59 patients were examined. Micrometastasis was found to be positive in 17 SLNs (14.0%) of 14 patients (23.7%). When examined number of sections was increased from one to three, more positive micrometastatic SLNs were detected by HE staining only (3, 7, 10 for 1, 2, 3 sections, respectively). When HE staining was combined with immunohistochemical staining for AE1/3 or CK19 or muc1, much more positive micrometastatic SLNs were found (14, 12, 16 for 1, 2, 3 sections, respectively). The more sections were examined, the more micrometastases in SLNs were found. Furthermore, micrometastasis was also found to be positively correlated with the tumor size and the expression of c-erbB2, MMP-2, VEGF. The larger the tumor size was or the stronger expression of the above mentioned biomarkers, the more micrometastases in SLNs could be found.

CONCLUSIONSerially sections at a 100 microm interval and staining with both HE and immunohistochemical technique using muc1 antibody may be the best way to detect micrometastases in sentinel lymph nodes in breast cancer patients.