Immune Suppression and Colorectal Cancer

Conclusion

This review highlights the many mechanisms whereby colorectal cancer induces immune suppression and how this relates to clinical prognosis (see Figure 2). Suppression begins at a molecular and cellular level and can result in a fundamental shift in immune function detectable in the systemic circulation. It is apparent that tumours use many different strategies to escape host immune responses and create an environment in which tumour cells can survive and proliferate. Here, we argue that the many mechanisms deployed strongly suggest that the immune system is capable of being very effective in containing colorectal tumours. Moreover, randomized-clinical trials have reported significant clinical benefits for an autologous cell-based vaccine^[19,20] and preoperative cytokine protocols have also been reported to make a significant difference.^[28,29] We therefore propose that the case for further studies with cancer vaccine and other immunotherapy candidates is overwhelming for Dukes' B disease and should be incorporated with standard adjuvant therapies for more advanced disease. Of note is the fact that current adjuvant regimens are remarkably non-immunosuppressive and would therefore be ideal for combination studies.^[214]

(Enlarge Image)

Potential changes to host immunity caused by colorectal cancer that result in poor prognosis. DC, dendritic cell; NK, natural killer; TGF, transforming growth factor; IL, interleukin; VEGF, vascular endothelial growth factor; COX, cyclo-oxygenase.

CLICK HERE for subscription information about this journal.

Aliment Pharmacol Ther. 2006;24(8):1163-1177. © 2006  Blackwell Publishing