Significance and problems of histopathological examination and utility of real-time reverse transcriptase-polymerase chain reaction method for the detection of sentinel lymph node metastasis in breast cancer.

Sentinel lymph node (SLN) biopsy has become a common procedure for breast cancer patients. Many reported feasibility studies have revealed a high identification (95.4% of 2,125 cases) and accuracy rate on histopathological analysis (94% frozen and 97% paraffin). However, about 5 to 8% of cases false-negative are in this examination. Various methods of histopathological examination have been reported by many authors, but the Philadelphia consensus meeting recommended that sections less than 2.0 mm in thickness should be prepared and examined to detect metastasis larger than 2.0 mm. In addition, immunohistochemistry for cytokeratin is considered to be useful to detect isolated tumor cells (ITC) in the representative sections. On the other hand, real-time reverse transcriptase-polymerase chain reaction (RT-PCR) might detect micrometastasis (larger than 0.2 mm) (sensitivity and specificity; 89.5% and 96.7% frozen sections) and expected to be used as a routine method instead of histopathological examination.