(P05-057-20) Dietary Carbohydrates, Fiber, Whole Grain and the Risk of Lung Cancer: Conclusions from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO)

Objectives: Inconsistent findings have been reported on the link between dietary carbohydrates and lung cancer incidence. We comprehensively evaluated the associations of dietary carbohydrates, fibers and their food sources with lung cancer in the PLCO Cancer Screening Trial.

Methods: The study included 113,096 eligible participants recruited to the PLCO trial. 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, fibers, whole grains, glycemic index (GI) and glycemic load (GL) for lung cancer.  Similar methods were applied in analyzing the food sources of carbohydrates and fibers. Multinomial logistic models were used for sensitivity analysis with lung cancer subtypes as outcomes.

Results: Dietary carbohydrates and GL were associated with a lower risk of lung cancer in the PLCO population. Among various carbohydrates, 30-gram daily consumption of dietary fibers was related to a lower risk of lung cancer (the fourth vs the first quartile OR: 0.62, 95% CI: 0.54-0.72) compared with 8.8-gram. Furthermore, consuming 2.3 servings of whole grain 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).  Nevertheless, a higher risk of lung cancer was seen for high-GI food consumption (P=0.013) and refined carbohydrates from soft drinks (P=0.016).

Conclusions: A higher quantity of high-quality carbohydrates and fibers from fruits, vegetables, and whole grains are associated with lower lung cancer risk. Refined carbohydrates, such as soft drinks, appear to increase risk.

Funding Sources: The University Postgraduate Fellowship from the University of Hong Kong