The role of cytokine gene polymorphisms in colorectal cancer and their interaction with aspirin use in the northeast of Scotland

The reduced risk of colorectal cancer associated with cyclooxygenase enzyme inhibitors, such as aspirin and other nonsteroidal anti-inflammatory drugs, strongly suggests that chronic inflammation is a key mediator in the development of colorectal cancer. This complements recent molecular evidence demonstrating an association between a number of proinflammatory genetic polymorphisms and risk of colorectal cancer. We assessed polymorphisms in the IL-1, IL-10, TNF-A, and TGF-B genes in a population-based case-control study of colorectal cancer cases (n = 264) and frequency-matched controls (n = 408) in the Northeast of Scotland and analyzed their interaction with regular aspirin use. There was no evidence of a relation between any of the individual polymorphisms, or pairs of polymorphisms, and risk of colorectal cancer. There was a significant interaction between the IL-10-592 C/A polymorphism and aspirin use (P-interaction = 0.03). Carriers of the variant IL-10-592 (A) allele, who produce less of the antiinflammatory cytokine interleukin-10, had a statistically significant 50% reduced risk of colorectal cancer when taking regular aspirin (odds ratio, 0.5; 95% confidence interval, 0.25-0.97), whereas risk was not reduced in carriers of the A allele who did not use aspirin, or among aspirin users with the CC genotype. It is possible that carriers of the mutant IL-10-592 allele are more likely to derive antiinflammatory and chemopreventive benefits from aspirin in the presence of a lower production of their own endogenous anti-inflammatory interleukin-10. These results suggest that host genetics may play a role in predicting response to chemopreventive strategies. Confirmation of these findings in other populations is required.