Western Diet, Family History of Colorectal Cancer, NAT2, GSTM-1 and Risk of Colon Cancer

Objective: In this study we examine the combined effects of Western diet, age at diagnosis, and genetic susceptibility. Methods: We use data collected as part of an incident case-control study of colon cancer. Family history of colorectal cancer, N-acetyltransferase (NAT2), and gluathione-S-transferase (GSTM-1) are studied with Western diet and age at diagnosis. Results: A significant interaction between age at time of diagnosis, Western dietary pattern, and family history of colorectal cancer (p for interaction = 0.03) was detected. Those with a family history of colorectal cancer who ate a predominantly Western diet were at increased risk of colon cancer (OR 14.0, 95% CI 3.9-50.1 for ≤55 years; OR 7.7, 95% CI 2.0-29.1 for 56-66 years; OR 1.6, 95% CI 0.8-3.2 for ≥67 years) compared to those without a family history of colorectal cancer and low levels of a Western diet. Associations with the Western diet were stronger than individual components of the dietary pattern. Neither NAT2 nor GSTM-1 showed significant interaction with Western diet. Conclusion: The extent to which diet comprising a Western dietary pattern influences risk of colon cancer is dependent on age. This dietary pattern also appears to modulate the colon cancer risk associated with a family history of colon cancer.