Dietary zinc, copper and selenium, and risk of lung cancer
Somdat Mahabir *
, Margaret R. Spitz, Stephanie L. Barrera, Shao Hua Beaver, Carol Etzel, Michele R. Forman
J Epidemiology
Department of Epidemiology, University of Texas M.D. Anderson Cancer Center,
*Correspondence to Somdat Mahabir, Department of Epidemiology-Unit 1340, CPB4.3241, 1155 Pressler Blvd., The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
Funded by:
Flight Attendant Medical Research Institute (FAMRI); Grant Number: CA 55769
Public Health Service; Grant Number: CA 86390
National Cancer Institute
National Institutes of Health
Department of Health and Human Services and Lung SPORE; Grant Number: CA70909
ABSTRACT
Zinc, copper and selenium are important cofactors for several enzymes that play a role in maintaining DNA integrity. However, limited epidemiologic research on these dietary trace metals and lung cancer risk is available. In an ongoing study of 1,676 incident lung cancer cases and 1,676 matched healthy controls, we studied the associations between dietary zinc, copper and selenium and lung cancer risk. Using multiple logistic regression analysis, the odds ratios (OR) and 95% confidence intervals (CI) of lung cancer for all subjects by increasing quartiles of dietary zinc intake were 1.0, 0.80 (0.65-0.99), 0.64 (0.51-0.81), 0.57 (0.42-0.75), respectively (p trend = 0.0004); similar results were found for men. For dietary copper, the ORs and 95% CI for all subjects were 1.0, 0.59 (0.49-0.73), 0.51 (0.41-0.64), 0.34 (0.26-0.45), respectively (p trend < 0.0001); similar reductions in risk and trend were observed by gender. Dietary selenium intake was not associated with risk, except for a significant inverse trend (p = 0.04) in men. Protective trends (p < 0.05) against lung cancer with increased dietary zinc intake were also found for all ages, BMI > 25, current smokers, pack-years 
30, light drinkers and participants without emphysema. Increased dietary copper intake was associated with protective trends (p < 0.05) across all ages, BMI, smoking and vitamin/mineral supplement categories, pack-years 30 and 30.1-51.75 and participants without emphysema. Our results suggest that dietary zinc and copper intakes are associated with reduced risk of lung cancer. Given the known limitations of case-control studies, these findings must be interpreted with caution and warrant further investigation.