Serum triglycerides and colorectal adenoma in a case-control study among cancer screening examinees (Japan)

Objective Most epidemiologic studies have shown serum triglycerides to be associated with colorectal adenoma. However, whether the association can be modified by smoking is unknown. We cross-sectionally investigated the association of serum triglycerides with the risk of adenoma by smoking status. Methods We identified 782 newly diagnosed adenoma cases from the examinees of a colorectal cancer screening program. All cases were diagnosed by a magnifying colonoscopy with dye spreading. We determined 738 controls without present illness or past history of adenoma from among the examinees. They provided their lifestyle information and fasting blood samples to measure their serum triglycerides. We calculated odds ratios (OR) and 95% confidence intervals (CI) of colorectal adenoma for serum triglycerides. Results High serum triglycerides were associated with colorectal adenoma (OR 1.5; 95% CI 1.1-2.0 for the highest versus the lowest quartile, P (trend,) 0.030). A stronger association was observed between three or more adenoma cases and study controls (OR 2.3; 95% CI 1.3-4.2, P (trend,) < 0.0010). After classifying the study subjects by smoking status, a significant linear risk trend was found in ever-smokers (P (trend), 0.0018) but not in never-smokers (P (trend), 0.94; P (interaction), 0.067). Conclusions Our results suggested that a higher serum triglyceride level may be related to a larger number of adenomas. Adenoma development involving an elevated serum triglyceride level may be modified by smoking.