Associations between Selected Dietary Factors, Selected Obesity-Related Metabolic Markers (Leptin, C-peptide, and High-sensitivity C-reactive Protein), and Lung Cancer: A Matched Case-Control Study Nested in the Prospective PLCO Trial

Abstract

The purpose of the study was to evaluate the associations between selected dietary factors, body mass index (BMI), selected obesity-related metabolic markers, and lung cancer risk as well as histological types in ever-smokers (former and current-smokers). Characteristics of interest included BMI at age 50, fruits and vegetables daily frequency, supplemental beta-carotene intake, C-peptide (CP), high-sensitivity C-reactive protein (hsCRP), and leptin concentrations. Data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial were analyzed. Linear regression models were used to describe the associations between quantitative variables. The relationships between variables of interest and lung cancer were studied by logistic regression modelling. Multivariable fractional polynomial (MFP) models were utilized to address non-linearity in these associations. Higher fruits and vegetables daily frequency and supplemental beta-carotene intake were associated with a lower risk of lung cancer in ever-smokers. Metabolic markers, C-peptide and hsCRP, were positively associated with lung cancer risk. Inverse relationships were observed between BMI and leptin with lung cancer risk. The relationships between selected dietary factors, BMI, selected metabolic markers, and lung cancer risk were more prominent in non-small cell lung cancer (NSCLC) in comparison with those in small cell lung cancer (SCLC).