Groin lymph node detection and sentinel lymph node biopsy in vulvar cancer

OBJECTIVE: To identify suitable diagnostic tools and evaluate the efficacy of sentinel lymph node (SLN) biopsy for inguinal lymph node metastasis in vulvar cancer. METHODS: Data from 41 patients with vulvar cancer were evaluated retrospectively, including magnetic resonance imaging (MRI) measurements, SLN biopsy status, groin lymph node metastasis, and prognosis. RESULTS: SLN biopsy was conducted in 12 patients who had stage I to III disease. Groin lymphadenectomy was omitted in five of the nine patients with negative SLNs. All SLN-negative patients who did not undergo groin lymphadenectomy showed no evidence of disease after treatment. On MRI, the long and short diameters of the inguinal node were significantly longer in metastasis-positive cases, compared with negative cases, in 25 patients whose nodes were evaluated pathologically (long diameter, 12.8 mm vs. 8.8 mm, p=0.025; short diameter, 9.2 mm vs. 6.7 mm, p=0.041). The threshold of >10.0 mm for the long axis gave a sensitivity, specificity, positive predictive value, and negative predictive value of 87.5%, 70.6%, 58.3%, and 92.3%, respectively, using a binary classification test. Decision tree analysis revealed a sensitivity, specificity, and accuracy of 87.5%, 70.6%, and 76.0%, respectively, with the threshold of >10.0 mm for the long axis on MRI. The criteria of >10.0 mm for the long axis on MRI predicted an advanced stage and poorer prognosis using a validation set of 15 cases (p=0.028). CONCLUSION: Minimally invasive surgery after preoperative evaluation on MRI and SLN biopsy is a feasible strategy for patients with vulvar cancer.