Clinicopathological significance of sentinel node biopsy in Japanese patients with cutaneous malignant melanoma.

Sentinel node biopsy (SNB) for malignant melanoma began to be performed in our department in 1997. A total of 121 patients underwent SNB. Sentinel node (SN) were identified in 39 (83.0%) of the 47 cases in which the blue dye method alone was used, and in 71 (95.9%) of the 74 cases by combination of dye, radioisotope, and γ probe methods. The excised SN was cut through its longest meridian, and the cut surfaces were stained with hematoxylin and eosin (HE) and examined for the presence (SN(+) ) or absence (SN(-) ) of melanoma cells. If no melanoma cells were detected, serial sections were prepared and examined by sequential staining with HE, for S-100 protein, with HE, for HMB-45, with HE, and for Melan-A. In this study minute metastasis (SNm(+) ) was defined as tumor cells newly identified in the immunostained section. The thickness of tumors ranged 0-38.0 mm, and their mean thickness was 4.5 mm. There were 39 SN(+) cases (39/110 [39+71]; 35.5%) and seven SNm(+) cases (7/110 [39+71]; 6.4%). The 5-year survival rate was significantly higher in the SN(-) group than in the SN(+) group and SNm(+) group combined (P=0.0002). The survival rate of the SNm(+) group was not significantly different from that of the SN(+) group (P=0.3848). The 5-year survival rate of the SN(+) group and SNm(+) group combined was significantly higher than that of the group with clinically unequivocal metastatic nodes (P=0.0001). Accurate SNB results will provide important prognostic information for Japanese patients with melanoma.