Tumor proliferation in squamous cell carcinoma of the vulva

Tumor proliferation is of important prognostic significance for several neoplasms. The very few previous studies on this parameter in vulvar carcinoma have shown contradictory results. The aim of this study was to determine the prognostic significance of tumor proliferation in vulvar carcinoma. Paraffin-embedded tissue of 74 squamous cell carcinomas of the vulva was immunostained for MIB-1, detecting Ki-67, and analyzed for staining patterns and the percentage of positive cells. There were three general staining patterns: a diffuse distribution (diffuse type), a localized staining at the infiltrating tumor border (infiltrating type), and a localized staining in basal parts of infiltrating tumor cell aggregates (basal type). The percentage of positive cells was not correlated with morphologic or clinical parameters, nor was it correlated with disease-free and overall survival. MIB-1 staining types were correlated with tumor type and grading. Tumors of diffuse and infiltrating type seemed to have more frequent lymph node metastasis (p = 0.053) and shorter disease-free survival (p = 0.076). In these tumors, overall survival time was reduced significantly (p = 0.02). In multivariate analysis, MIB-1 staining types were the most important factor for overall survival with an odds ratio of 4.73. In conclusion, distribution and not the percentage of proliferating cells is of prognostic significance in squamous cell carcinoma of the vulva.