[Detecting micrometastases in sentinel lymph nodes]

Many investigators have reported micrometastases in sentinel lymph nodes, which have been detected by various methods. The most common method of detecting micrometastases is pathological examination using a combination of hematoxylin-eosin and immunohistochemical staining of multisectioned specimens. However, no standard method has been established concerning how to slice the specimen and how many slides should be examined. On the other hand, a more sensitive method utilizing the reverse-transcriptase polymerase chain reaction (RT-PCR) has also been applied for the detection of micrometastases. However, this method is so sensitive that it may detect isolated tumor cells (ITC), which are not defined as metastases according to the 6th edition of the American Joint Committee on Cancer and Union Internationale contre le Cancer cancer staging manuals for breast cancer. Therefore it is an urgent task to establish a standard method for detecting micrometastases in sentinel lymph nodes. For this purpose, further examination of many patients is needed to determine the most efficient and convenient way for detection of micrometastases in sentinel lymph nodes, whether the micrometastases influences the prognosis of patients, and whether regional lymph node clearance is needed in the case of micrometastases in sentinel lymph nodes.