Serum Concentrations of Fatty Acids and Colorectal Adenoma Risk: A Case-Control Study in Japan

Background: Epidemiologic studies of n-3 fatty acids (FAs) and risk of colorectal cancer have generatedinconsistent results, and relations with precursor colorectal adenomas (CRA) have not been evaluated in detail.We here focused on possible associations of serum FAs with CRA in the Japanese population.
Methods: Weconducted a case-control study of 203 asymptomatic CRA cases (148 men, 55 women) and 179 healthy controls(67 men, 112 women) during 1997-2003 in Nagoya, Japan. Baseline information was obtained using a lifestylequestionnaire and serum FA levels were measured by gas chromatography.
Results: A non-significant inverseassociation with CRA was observed for eicosapentaenoic acid (EPA) among women. Moreover, the concentrationsof docosahexaenoeic acid (DHA), a major component of n-3 highly-unsaturated FAs (HUFAs), were significantlylower in cases in both sexes. In addition, serum concentrations of total FAs, saturated FAs (SFAs) and monounsaturatedFAs (MUFAs) had strong positive links with CRA risk. In contrast, arachidonic acid (AA) andDHA were inversely related, with 66% and 59% risk reduction, respectively. Ratios of SFAs/n-3 PUFAs andSFAs/n-3 HUFAs exhibited significant positive relations with CRA risk but there was no clear link with n-6PUFAs/n-3 PUFAs.
Conclusions: Our findings suggest a promoting influence of SFAs and MUFAs along with aprotective effect of DHA on CRA risk. However, further research is needed to investigate the observed discrepancywith the generally accepted roles of the AA cascade in carcinogenesis.