Risk factors for the development of lymph node metastasis in vulvar squamous cell carcinoma.

One hundred and ten women who underwent vulvectomy and inguinal-femoral lymphadenectomy for stages I-IV vulvar squamous cell carcinoma were studied. The most important factors that affected the inguinal lymph node status in the order of importance were vascular invasion, clinical stage, tumor thickness, depth of stromal invasion, and amount of keratin. Fourteen (88%) of 16 tumors with vascular invasion in the primary tumor metastasized. In the absence of vascular invasion, 18 (19%) of 94 tumors metastasized. Overall, 82% of tumors were correctly classified into lymph node negative and positive groups on the basis of vascular invasion. Tumor thickness and depth of stromal invasion had a similar accuracy in predicting lymph node status. The risk of lymph node metastasis increased from 0% when tumor thickness or depth of stromal invasion was less than 2 mm, to over 20% when depth of stromal invasion was greater than 2 mm, and to over 40% when tumor thickness exceeded 4 mm. A combination of vascular invasion, tumor thickness (or depth of stromal invasion), and the amount of keratin correctly classified 97% (76/78) of the lymph node negative group and 63% (20/32) of the positive group with an overall accuracy of 87%. The probability of having lymph node metastasis was computed for individual patients on the basis of one or more pathologic parameters using a logistic regression model. This feasibility is an important step toward individualized therapy for vulvar carcinoma.