Sentinel lymph node biopsy in breast cancer: an overview of the Japanese experience

This paper reviews the Japanese literature regarding sentinel lymph node (SLN) biopsy in an attempt to provide an overview of existing controversies and to suggest a method for the identification of the SLN and the detection of micrometastases in the SLN to eliminate unnecessary axillary lymph node dissection (ALND). The combined dye- and gamma probe-guided method resulted in the accurate identification of the SLN in 96% of patients, compared with 80% when the dye-guided method alone was used. Although neither 99m-Tc sulfur colloid nor 99m-Tc colloidal albumin is commercially available in Japan, 99m-Tc stannous phytate and 99m-Tc rhenium colloid appear to be ideal tracers for identifying SLNs. Moreover, subdermal injection over the primary tumor or subareolar injection was found to enhance SLN identification, although these injection routes do not lead to detection of internal mammary SLNs. Furthermore, the accuracy of SLN diagnosis using frozen sections as well as imprint cytology improved with an increase in the number of sections, and could attain a sensitivity comparable to that obtained with routine histologic examination of permanent sections. As a result, several surgeons have begun to offer the option of forgoing ALND to patients with negative SLN. Although subsequent relapse in the axilla has not yet been reported, longer follow-up periods are needed to assess accurately the incidence of axillary failure in these negative SLN patients.