A case-control study of dietary factors in patients with lung cancer

A case-control study was designed to investigate association of dietary factors with the risk of lung cancer in Sichuan, China. The cases consisted of 135 patients with preinvasive lung cancer which had been confirmed with histopathology, fiber bronchoscope, CT and X-ray film in three provincial hospitals in the recent one year. Controls were healthy subjects who went to one of these hospitals for health check-up; patients with pulmonary diseases was excluded. Controls were matched to cases for sex and age with a ratio of 1:1. Nutrient intakes, the eating habit and other relevant factors were investigated. The data analyzed with the conditional logistic regression model indicated that dietary beta-carotene intakes had a significantly inverse association with the risk of lung cancer. Vitamin C had a less significantly inverse association with the risk. Association of protein, fat, energy, retinol intakes or diet-balance index with the risk was not significant. Association of tea, alcohol, garlic or mushroom, respectively, with the risk was also not observed. Consumption of more processed foods and deep-fried foods were found to be risk factors. Smoking and air pollution from coal burning stoves were also observed as independent risk factors of lung cancer in the present study. The mental stress incidence in the case was significantly higher than that in the control.