Variation of microsomal mixed function oxidase(s) and human lung cancer.

Animal and human studies on aryl hydrocarbon hydroxylase (AHH) have demonstrated wide inter-individual variation. First attempts to link this variation to the susceptibility to certain cancers have been successful in mice but remained inconclusive in man. In a new approach, saliva antipyrine half-lives and metabolic clearance rates have been used to assess individual rates of benzo]a]pyrene metabolism in human subjects. Saliva antipyrine half-lives and metabolic clearance rates have been measured in 57 patients with lung cancer, 90% of whom had quit smoking more than three months prior to the test, 57 cancer-free matched controls, and 59 healthy smoking controls. The mean antipyrine half-life was significantly shorter (P less than 0.001) in lung cancer patients when compared with the cancer-free matched control group, but differed little from that of the smoking group (P less than 0.05). The data support the previous observation than lung cancer patients have increased oxidation rates which, in addition to smoking, might have predisposed them to developing lung cancer.