• School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
• Department of Oncology, Mayo Clinic, Rochester, MN, USA.
• Duke Cancer Institute, Duke University Medical Center, Durham, USA.
• School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Jockey Club Institute of Cancer Care, The University of Hong Kong, Hong Kong, China.
• Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
• Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, USA.
• School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, USA. Electronic address: herbpang@hku.hk.

OBJECTIVES: Inconsistent findings have been reported on the link between dietary carbohydrates and lung cancer. This study aims to comprehensively evaluate the role of dietary carbohydrates on lung cancer risk.

MATERIALS AND METHODS: The prospective study is based on the PLCO trial, which recruited 113,096 eligible participants across the United States. Participants had to have completed baseline and diet history questionnaires. The incidence of lung cancer was acquired through self-report and medical record follow-up. A multivariable logistic model adjusted for confounders was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs) of dietary carbohydrates, fiber, whole grains, glycemic index (GI) and glycemic load (GL) for lung cancer. Similar methods were applied in analyzing the carbohydrates and fiber from different food sources. Multinomial logistic models were used for sensitivity analysis with lung cancer subtypes as outcomes.

RESULTS: Dietary carbohydrates and GL were inversely associated with lung cancer incidence in the PLCO population. Among various carbohydrates, 30-g daily consumption of dietary fiber was related to a lower risk of lung cancer (fourth vs first quartile OR: 0.62, 95 % CI: 0.54-0.72) compared with 8.8-g. Furthermore, consuming whole grains 2.3 servings per day as opposed to 0.3 servings per day was associated with a lower risk of lung cancer (OR: 0.73, 95 % CI: 0.64-0.83). A higher risk of lung cancer was seen for the consumption of high-GI food (OR: 1.19, 95 % CI: 1.05-1.35) and refined carbohydrates from soft drinks (OR: 1.23, 95 % CI: 1.04-1.46).

CONCLUSION: Carbohydrates and fiber from fruits, vegetables and whole grains are associated with lower lung cancer risk. Refined carbohydrates from processed food, such as soft drinks, appear to increase risk.