Relevance of CD4+ and CD8+ tumor-infiltrating lymphocytes and Foxp3 as prognostic factors in papillary thyroid carcinoma: new mission for immunotherapy

Background There is increasing evidence supporting the prognostic significance of tumor-infiltrating lymphocytes as CD4, CD8, and forkhead box P3 (Foxp3)-expressing regulatory T cells in different cancers, however, their significance in thyroid cancer remains uncertain. Aims We investigated the expression of CD4, CD8, and Foxp3 in papillary thyroid carcinoma (PTC) and assessed its prognostic implications. Study design It is a retrospective study carried out on 43 PTC cases that were retrieved from archives of pathology lab of Oncology Center, Mansoura University, Egypt. Materials and methods Immunostaining for CD4, CD8, and Foxp3 was done. Results We found that CD4/CD8 expression was significantly higher among patients with higher lymph-node stage and more extranodal extension (P=0.038 and 0.043, respectively). Disease-free survival was found to be shorter among patients with high CD4/CD8 ratio compared with patients with low ratio (P=0.014). As regards Foxp3, there was a difference in its expression between neoplastic and nonneoplastic tissues. Both disease-free survival and overall survival were found to be shorter among patients with positive Foxp3 in tumor and tumor-infiltrating lymphocytes compared with patients with negative Foxp3 in both. Conclusions CD4/CD8 ratio and Foxp3 could be used as predictive markers and as a target therapy for PTC.