Scottish scientists have discovered that a single gene may decide whether or not a smoker develops lung cancer.

The gene regulates bodily defences against the carcinogenic compounds found in all cigarettes ( even if the American tobacco companies say their product is safe...).

Professor Roland Wolf, said: " It has long been known that our bodies contain factors which determine our sensitivity to cancer-causing chemicals. " Now we've shown for the first time that a single gene could be profoundly important in protecting us against cancer. That is good news, because it is easier to manipulate one gene than many. "