Associations of dietary polyunsaturated fatty acids and sleep patterns with lung cancer in southwest China: A case-control study

Background Evidence on the associations of polyunsaturated fatty acid (PUFA) intake and sleep patterns with lung cancer remains inconsistent. We aimed to examine these associations in southwest China and to explore whether the association between sleep patterns and lung cancer differed according to dietary PUFA intake. Methods We conducted a matched case-control study in Chongqing, southwest China, from August 22, 2023, to September 30, 2024. Each lung cancer case was matched to two controls by age group (65 years) and sex. Dietary PUFA intake was assessed using a validated semi-quantitative food frequency questionnaire (SQFFQ), and sleep patterns were evaluated using a composite healthy sleep score based on five sleep characteristics. Multivariable conditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Results A total of 322 lung cancer cases and 644 matched controls were included. In continuous analyses, each 1-g/day increase in omega-3 PUFA intake was associated with lower odds of lung cancer (OR = 0.82, 95% CI: 0.70–0.96). In tertile-based analyses, participants in the highest versus lowest intake tertiles had lower odds of lung cancer across all three PUFA types (omega-3 PUFAs: OR = 0.50, 95% CI: 0.32–0.78; omega-6 PUFAs: OR = 0.50, 95% CI: 0.31–0.80; total PUFAs: OR = 0.48, 95% CI: 0.30–0.79). Favorable sleep patterns were also associated with lower odds of lung cancer compared with unfavorable sleep patterns (OR = 0.59, 95% CI: 0.40–0.87). Although lower stratum-specific ORs were observed in the higher omega-3 PUFA intake stratum, the multiplicative interaction tests were not statistically significant. Conclusion Higher dietary omega-3 PUFA intake and favorable sleep patterns were each associated with lower odds of lung cancer in this matched case-control study. Associations for omega-6 and total PUFA intake were observed in tertile-based analyses but were not consistent across modeling approaches. These observational findings require confirmation in prospective studies.