Background: Patients with chronic inflammatory bowel disease (IBD) are at an increased risk of colorectal cancer (CRC) and it is estimated that one in six persons diagnosed with IBD will develop CRC. This fact suggests that genetic variations in inflammatory response genes may act as CRC disease risk modifiers.
Methods: In order to test this hypothesis we investigated a series of polymorphisms in 6 genes (NOD2, DLG5, OCTN1, OCTN2, IL4, TNFalpha) associated with the inflammatory response on a group of 607 consecutive newly diagnosed colorectal cancer patients and compared the results to controls (350 consecutive newborns and 607 age, sex and geographically matched controls).
Results: Of the six genes only one polymorphism in TNFalpha(-1031T/T) showed any tendency to be associated with disease risk (64.9% for controls and 71.4% for CRC) which we further characterized on a larger cohort of CRC patients and found a more profound relationship between the TNFalpha -1031T/T genotype and disease (64.5% for controls vs 74.7% for CRC cases above 70 yrs). Then, we investigated this result and identified a suggestive tendency, linking the TNFalpha -1031T/T genotype and a previously identified change in the CARD15/NOD2 gene (OR = 1.87; p = 0,02 for CRC cases above 60 yrs).
Conclusion: The association of polymorphisms in genes involved in the inflammatory response and CRC onset suggest that there are genetic changes capable of influencing disease risk in older persons.