Dietary glycemic index, glycemic load intake, and risk of lung cancer: A meta-analysis of observational studies

This meta-analysis evaluated the relationship between dietary glycemic index (GI), glycemic load (GL), and lung cancer risk, which has been controversial in previous studies. We searched PubMed, Embase, Web of Science, and Cochrane Library databases for relevant studies from inception to October 2021 in English only. We included case-control and cohort studies that reported relative risks (RRs) and 95% confidence intervals (CI) between dietary GI or GL intake and lung cancer risk. Either a fixed- or random-effects model was used to estimate pooled RRs. Subgroup analysis, sensitivity analysis, meta-regression, publication bias test, and dose-response meta-analysis were performed. We identified nine studies eligible for meta-analysis with 32810 cases and 351013 controls. The pooled RR for highest versus lowest intake was 1.14 (95% CI: 1.03-1.26, I2=64.8%, P=0.002) for GI and 0.93 (95% CI: 0.84-1.02, I2=42.3%, P=0.076) for GL. Subgroup analysis showed that the associations between GI or GL and lung cancer were similar between groups. Sensitivity analysis revealed reduced heterogeneity among GL-related studies when one particular study was excluded. There was no evidence of publication bias. A linear association between GI intake and lung cancer risk was observed. The present meta-analysis suggests that high dietary GI intake is associated with a significantly increased risk of lung cancer in a linear fashion. However, no significant association was observed between GL and lung cancer risk.