Former smokers constitute almost half of all newly-diagnosed lung cancer cases. Smoking inflicts serious damage to the lungs that do not disappear as soon as people quit, as it takes time for the tissue to recover. It has also been found that smoking causes genetic damage in the form of loss of a gene that could protect cells from becoming cancerous. Researchers from the University of Texas have now shown that a close chemical relative of vitamin A restores the function of this gene called retinoic acid receptor (RAR) beta. This chemical compound, called s-retinoic acid (RA), was tested on a group of former smokers that was given either RA or placebo for three months. A lung biopsy that was taken later showed that there was a marked increase in the activity of RAR in the active treatment group. The researchers claim that, though this study did not prove that RA prevents cancer in former smokers, this is the first time the benefit of chemoprevention (preventive treatment by a drug) has been demonstrated in a group.