The CancerWeb Report, What's New In Cancer: July, 1996
Lung Cancer

• Is increased retinoid breakdown a factor in developing lung cancer? - A report in the June 15, 1996 issue of Cancer Research suggests that those who metabolize the retinoid all-trans- retinoic acid very rapidly have greater risk of lung cancer. The researchers at the Memorial Sloan-Kettering Cancer Center in New York studied 89 lung-cancer patients and controls given a standard dose of all-trans retinoic acid. They compared the areas under the curves they obtained by plotting the time course of plasma levels of the retinoid; these areas are smaller the faster the drug concentrations fall due to metabolism. Those with areas below a certain value (250 units) had nearly a six- fold increased risk of having squamous or large cell lung cancer. (Rigas, Cancer Res 56:2692, 1996)

  Editor's Comment: - Retinoids appear to play a role in maintaining epithelial tissues in a normal state. All-trans retinoic acid has been shown to prevent cancer from developing in experimental studies with carcinogenic chemicals, and there is some evidence that it can do this in humans too, but the data are not so convincing. If levels of retinoids are low in some individuals because of high metabolic rate, these people might be less capable of protecting themselves against the effects of carcinogens. Perhaps by taking whole groups of people with differing abilities to metabolize retinoids for retinoid studies, we are not able to distinguish this protective effect. As the authors of the article speculate, those with increased ability to break down retinoids might be the ones to benefit from retinoid supplements, not the general population.