Tumor-infiltrating FoxP3 Tregs predict favorable outcome in colorectal cancer patients: A meta-analysis.

FoxP3 regulatory T cells (FoxP3 Tregs) are considered to be a key mediator in immune escape and tumor progression. However, the role of FoxP3 Tregs in human colorectal cancer (CRC) remains controversial. Herein, we conducted a meta-analysis including 17 published studies with 3811 patients identified from PubMed and EBSCO to assess the prognostic impact of tumor-infiltrating FoxP3 Tregs in human CRC. We found FoxP3 Tregs infiltrating into both intraepithelium and stroma within tumor were significantly positively correlated with 1, 3, 5 and 10-year overall survival (OS), but not with 1, 3, 5-year disease-free survival (DFS) of patients. Interestingly, in stratified analyses by compartments within tumor FoxP3 Tregs infiltrating into, FoxP3 Tregs invading stromal compartment significantly improved 3 and 5-year OS, yet OS wasn't improved when FoxP3 Tregs infiltrated into intraepithelium only. Furthermore, FoxP3 Tregs invading both intraepithelium and stroma significantly inversely correlated with TNM stage of CRC. In conclusion, High density of FoxP3 Tregs within tumor especially at stromal compartment leads to a favorable outcome in CRC, implicating FoxP3 Tregs are one of valuable indexes for prognostic prediction in human CRC.