[Chemoprevention of tobacco-related lung cancer by cruciferous vegetable].

Lung cancer is the most common malignant disease in the world and the major cause of death from cancers. Around 80-90% of all human lung cancers are related to cigarette smoke. Tobacco smoke contains at least 60 carcinogens capable of causing tumors, 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and polycyclic aromatic hydrocarbons (PAH) are among the most prominent pulmonary carcinogens. Prevention is the most effective way to reduce lung cancer mortality. Chemoprevention is a cancer preventive strategy to inhibit, delay or reverse carcinogenesis using naturally occurring or synthetic chemical agents. A number of epidemiological studies have shown an inverse relationship between cruciferous vegetable consumption and cancer, especially those of lung and stomach. Crucifers, such as broccoli, cauliflower, brussel sprouts and cabbage, contain a family of secondary plant metabolites known as glucosinolates, which are unique to these vegetables. Upon hydrolysis, glucosinolates yield a number of breakdown products, mostly isothiocyanates, with supposed chemopreventive properties, as shown in animal experiments. It appears that significant portion of the chemopreventive effects of isothiocyanates may be associated with the inhibition of the metabolic activation of carcinogens by cytochrome P450s (Phase I), coupled with strong induction of phase II of detoxifying enzymes.