Objective: To investigate an optimal examination method to detect micrometastases in sentinel lymph nodes (SLNs) of breast cancer.
Methods: Firstly, 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.
Results: Totally, 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.
Conclusion: Serially 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.