Improved Detection of Metastases by Step Sectioning and Immuno-Histochemical Staining of Axillary Sentinel Nodes in Patients with Breast Carcinoma

Background: The object of this study was to examine whether a new protocol including step-sectioningand immunohistochemistry (IHC) staining of axillary sentinel nodes (SN) would lead to detection of moremetastases in patients with breast cancer. Materials and
Methods: Sixty-nine tumor free sentinel lymph nodeswere examined. Step frozen sectioning was performed on formalin fixed SN and stained both by hematoxylinand eosin (H and E) and cytokeratin markers using IHC. Any tumoral cell in IHC stained slides were consideredas a positive result. Metastases up to 0.2 mm were considered as isolated tumor cells and 0.2 up to 2 mm asmicrometastasis.
Results: Mean age of the patients was 48.7±12.2 years. Step sectioning of the SN revealed 11involved by metastasis which was statistically significant (p<0.001). Furthermore, 15 (21.7%) of the patientsrevealed positive results in IHC staining for pan-CK marker and this was also statistically significant (p=0.001).Ten patients had tumoral involvement in lymph nodes harvested from axillary dissection and 4 out of 15 lymphnodes with positive result for CK marker were isolated tumor cells. However, 4 of 10 patients with tumor positivelymph nodes in axillary dissection were negative for CK marker and in contrast 6 of the pan-CK positive SNwere in patients with tumor-free axillary lymph nodes.
Conclusions: Both IHC and step sectioning improve thedetection rate of metastases. Considering the similar power of these two methods, we recommend using eitherIHC staining or step sectioning for better evaluation of harvested SNs.