Multiple epidemiologic studies have evaluated the relationship between dietary cholesterol and lung cancer risk, but the association is controversial and inconclusive. A meta-analysis of case-control studies and cohort studies was conducted to evaluate the relationship between dietary cholesterol intake and lung cancer risk in this study. A relevant literature search up to October 2017 was performed in Web of Science, PubMed, China National Knowledge Infrastructure, Sinomed, and VIP Journal Integration Platform. Ten case-control studies and six cohort studies were included in the meta-analysis, and the risk estimates were pooled using either fixed or random effects models. The case-control studies with a total of 6894 lung cancer cases and 29,736 controls showed that dietary cholesterol intake was positively associated with lung cancer risk (Odds Ratio = 1.70, 95% Confidence Interval: 1.43–2.03). However, there was no evidence of an association between dietary cholesterol intake and risk of lung cancer among the 241,920 participants and 1769 lung cancer cases in the cohort studies (Relative Risk = 1.08, 95% Confidence Interval: 0.94–1.25). Due to inconsistent results from case-control and cohort studies, it is difficult to draw any conclusion regarding the effects of dietary cholesterol intake on lung cancer risk. Carefully designed and well-conducted cohort studies are needed to identify the association between dietary cholesterol and lung cancer risk.
To analyze the correlation between the serum estradiol and lung cancer in Chinese population, PubMed, the Cochrane database and the China National Knowledge Internet database as well as VIP, WANGFANG MED, Sino Med were comprehensively searched for related studies strictly according to the selection criteria. Statistical analysis was performed using Review Manager 5.3 software. 16 studies were included for analysis, of which there were 736 subjects in the lung cancer group, 544 ones in the healthy control group. The results of Meta-analysis showed that the serum estradiol levels were higher in the lung cancer group than in the control one (SMD=0.81, 95%CI 0.31-1.30, Z=3.20, P<0.01). Meanwhile, from the subgroup analysis, the level of serum estradiol was higher in male lung cancer group (SMD=0.62, 95%CI 0.03-1.21, Z=2.06, P<0.05), but not in the female lung cancer group (SMD=0.02, 95%CI -0.51-0.55, Z=0.06, P>0.05) compared to the healthy control groups. Therefore, the serum estradiol level in the patients with lung cancer is higher than that in the healthy control population, suggesting serum estradiol level may be associated with the pathogenesis of lung cancer and expected to become a marker for the diagnosis of lung cancer, especially in Chinese population.
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