Dietary vitamin A, beta carotene and risk of epidermoid lung cancer in south-western France.

This hospital-based case-control study was designed to investigate the association of low dietary vitamin A and beta carotene consumption with epidermoid lung cancer. Cases were patients with histologically confirmed epidermoid lung cancer diagnosed in six selected hospitals of southwestern France in 1983-84. Controls were selected from patients admitted to the same hospitals during the same period with diagnoses other than cancer. Cases and controls were matched for sex, age, place of residence, occupation, professional exposure to carcinogens, tobacco and alcohol consumption. A total of 106 cases of epidermoid lung cancer and 212 controls were interviewed on their typical weekly intake of 80 food items rich in preformed vitamin A and beta carotene. Index measures of the vitamin A and beta carotene daily intakes were computed for each individual patient and expressed in retinol equivalent (RE). A statistically significant odds ratio (OR) was found for preformed vitamin A (OR = 4.3; 95% CI: 2.5-7.3) with the threshold of 1,000 RE. A similar result was found for beta carotene with the same threshold (OR = 4.1; 95% CI: 2.3-7.4). Using the conditional logistic regression, consumption of preformed vitamin A and consumption of beta carotene were significantly and independently associated with epidermoid lung cancer. While confirming the protective role of beta carotene against epidermoid lung cancer, this study also shows that preformed vitamin A might have a distinct and important protective effect.