Immunological and Clinical Impact of Cancer Stem Cells in Vulvar Cancer: Role of CD133/CD24/ABCG2-Expressing Cells

Background: Cancer stem cells (CSCs) are tumour-initiating cells with self-renewal properties and chemo/radio-resistance. Regulatory T-cells (Tregs) influence CSCs through several mechanisms. In different solid tumours, the presence of both cell populations correlated with poor survival. In vulvar cancer, little is known regarding biological markers able to predict patient prognosis. We investigated the presence and clinical impact of CSCs and infiltrating Treg in primary vulvar cancer. Materials and Methods: Paraffin-embedded tissue specimens derived from 43 patients with vulvar cancer were analyzed by immunohistochemistry for the expression of prominin-1 (CD133), CD24, ATP-binding cassette sub-family G member 2 (ABCG2) (CSC markers) and forkhead box protein P3 (FOXP3) (Treg marker). Results: CD133 expression correlated with younger age at diagnosis (p<0.01), lymph-node metastasis (p<0.05) and larger tumour diameter (p<0.05). CD133+ tumours showed a high FOXP3+ T-cell infiltration. Overall survival and progression-free survival were not influenced by the expression of the analyzed biomarkers. Conclusion: In vulvar cancer, CSCs were more frequently expressed in younger aged patients and those with aggressive disease. Their presence was also associated with high Treg infiltration, which contributes to the generation of an immunosuppressive milieu.