Foxp3+ regulatory T cells and the formation of portal vein tumour thrombus in patients with hepatocellular carcinoma

Background: Most patients with hepatocellular carcinoma (HCC) have advanced-stage disease at diagnosis. The prognosis for patients with HCC is very poor, especially for those with portal vein tumour thrombi (PVTT). The purpose of our study was to observe the prognostic value of PVTT and tumour-infiltrating regulatory T cells (Tregs) and the correlation between them. Methods: We examined 76 HCC specimens by immunohistochemistry for CD4+, CD8+ T cells and Foxp3+ Tregs. The survival of patients was prospectively followed up. Patients with HCC were grouped according to the formation of PVTT or Treg infiltration status. We performed a Kaplan-Meier survival analysis to observe the difference in prognosis between the groups. We analyzed the correlation of Treg expression with clinical and pathologic features. Results: Survival analysis revealed that both the disease-free survival rate and total survival rate after hepatic resection were significantly lower in patients in the PVTT group than those in the non-PVTT group (p = 0.026 and p = 0.022, respectively). Likewise, both the disease-free survival rate and the total survival rate were significantly lower in patients in the high Treg group than those in the low Treg group (p = 0.012 and p = 0.023, respectively). We found that intratumoural Tregs were associated with PVTT formation (p = 0.001) and that patients with high Treg infiltration had a higher percentage of PVTT formation. Conclusion: Patients with PVTT formation or high intratumoural Treg infiltration tended to have a poor prognosis. Intratumoural Treg was associated with formation of PVTT in patients with HCC.