Erythrocyte ω-3 polyunsaturated fatty acids are inversely associated with the risk of oral cancer: a case-control study

OBJECTIVES: Evidence about ω-3 polyunsaturated fatty acids (ω-3 PUFAs) and oral cancer risk were limited. We aimed to evaluate the association of erythrocyte ω-3 PUFAs with the risk of oral cancer in a population from China. METHODS: Erythrocyte ω-3 PUFAs of 236 oral cancer patients and 300 controls were determined by gas chromatography. Restricted cubic spline and logistic regression were used to analyze the association between erythrocyte ω-3 PUFAs and oral cancer risk. The crude and adjusted OR with 95% CI was calculated. Stratification analysis was performed to explore the potential interaction between ω-3 PUFAs and other traditional risk factors such as smoking and drinking. RESULTS: Eicosapentaenoic acids (EPA), docosahexaenoic acids (DHA) and ω-3 index were negatively but non-linearly related to risk of oral cancer as observed by restricted cubic spline. The adjusted OR of EPA, DHA, and ω-3 index were 0.52 (95% CI: 0.35–0.76), 0.19 (95% CI: 0.08–0.44), 0.20 (95% CI: 0.09–0.44), respectively. Stratification analysis showed that the adverse correlation between EPA and oral cancer was only significant in the non-smoking group, while the adverse correlation of ɑ-linolenic acid (ALA), EPA, and DHA were only significant in the non-drinking group. General multiplicative interactions were observed between ω-3 PUFAs and smoking or drinking. CONCLUSIONS: Adverse but non-linear associations were observed between erythrocyte EPA, DHA, ω-3 index, and oral cancer risk. Additionally, there were multiplicative interactions between ω-3 PUFAs and other behavior factors such as smoking and drinking. The protective effect of ω-3 PUFAs maybe more significant in the non-smoking or non-drinking population.