Glycemic index, glycemic load, and lung cancer risk in non-hispanic whites

Background: Postprandial glucose (PPG) and insulin responses play a role in carcinogenesis. We evaluated the association between dietary glycemic index (GI) and glycemic load (GL), markers of carbohydrate intake and PPG, and lung cancer risk in non-Hispanic whites. Methods: GL and GI were assessed among 1, 905 newly diagnosed lung cancer cases recruited from the University of TexasMD Anderson Cancer Center (Houston, TX) and 2,413 healthy controls recruited at Kelsey-Seybold Clinics (Houston, TX). We assessed associations between quintiles of GI/GL and lung cancer risk and effect modification by various risk factors. ORs and 95% confidence intervals (CI) were estimated using multivariable logistic regression. Results: We observed a significant association between GI [5th vs. 1st quintile (Q) OR=1.49; 95% CI, 1.21-1.83; P_trend <0.001] and lung cancer risk and GI_ac (5th vs. 1st Q OR=1.48; 95% CI, 1.20-1.81; P_trend=0.001) and lung cancer risk. We observed a more pronounced association between GI and lung cancer risk among never smokers (5th vs. 1st Q OR=2.25; 95% CI, 1.42-3.57), squamous cell carcinomas (SCC; 5th vs. 1st Q OR=1.92; 95% CI, 1.30-2.83), and those with less than 12 years of education (5th vs. 1st Q OR=1.75; 95% CI, 1.19-2.58, P_interaction=0.02). Conclusion: This study suggests that dietary GI and other lung cancer risk factors may jointly and independently influence lung cancer etiology. Impact: Understanding the role of GI in lung cancer could inform prevention strategies and elucidate biologic pathways related to lung cancer risk. Cancer Epidemiol Biomarkers Prev; 25(3); 532-9.