Objective:To explore the changes and possible mechanisms of circulating Tc 17 cells in patients with colorectal cancer ( CRC) following disease progression .Methods:The peripheral blood were collected from 54 patients with colorectal cancer . the proportions of Tc17 cells in peripheral blood mononuclear cells (PBMCs) and cultured PBMCs treated by IL-1β, IL-6 and TGF-βin different concentrations were determined by flow cytometry;the levels of IL-1β, IL-17A, IL-23 and IL-6 in sera were measured by ELISA.Results:The proportions of Tc17 cells and the levels of IL-1β, IL-17A, IL-23 and IL-6 were significantly higher than those in healthy controls (P<0.05).Compared with early CRC, the proportions of Tc17 cells and the levels of IL-1β, IL-17A in advanced CRC were significantly decreased, but the level of IL-6 was significantly increased (P<0.05).The difference of IL-23 level between early and late groups was not significant (P>0.05).In vitro experiments confirmed that IL-1βor high concentrations of IL-6 and TGF-βcould significantly increase the number of Tc 17 cells in PBMCs.Conclusion: The changes of circulating Tc 17 cells in the progression of colorectal cancer are possibly modulated by IL-1β, IL-23, IL-6 and TGF-β.