Blood lipids profile and lung cancer risk in a meta-analysis of prospective cohort studies.

BACKGROUND: Emerging evidence has connected lipid metabolism disturbance with lung diseases, but the relationship between blood lipid profile and lung cancer risk is controversial and inconclusive.

OBJECTIVE: We conducted a meta-analysis of prospective cohort studies to evaluate the relationship between blood lipids profile and lung cancer incidence.

METHODS: Relevant studies were identified by searching PubMed, Cochrane Library, Web of Science, EBSCO, Ovid, CNKI, VIP, and WANGFANG MED through August 2016. Nine prospective cohort studies were included in the meta-analysis, and fixed or random effects model was used to calculate pooled relative risk (RRs). The RR was calculated using either highest vs lowest categories, or upper quantile vs lowest quantile. The thresholds were determined by the authors of each original publication, based on either predefined cut-offs or the distributions within their study population.

RESULTS: Analysis of 18,111 lung cancer cases among 1,832,880 participants showed that serum total cholesterol levels were inverse associated with lung cancer risk (RR = 0.93, 95% confidence interval [CI]: 0.85-1.03). Further analysis considered the lag time and excluded the effects of preclinical cancer, with totally 1,239,948 participants and 14,052 lung cancer cases, found a significantly inverse association between total cholesterol and lung cancer risk (RR = 0.89, 95% CI: 0.83-0.94). Analysis of 3067 lung cancer cases among 59,242 participants found that the high-density lipoprotein cholesterol levels (RR = 0.76, 95% CI: 0.59-0.97) was negatively associated with lung cancer risk and 4673 lung cancer cases among 685,852 participants showed that the total triglyceride (RR = 1.68, 95% CI: 1.44-1.96) was positively associated with lung cancer risk.

CONCLUSION: Cholesterol and fatty acid metabolism might present different and specific mechanism on lung cancer etiology and needs further elucidation.