In comparison, chemo can give newly diagnosed lung cancer patients an extra two to three months of life, says study co-author Thomas Lynch, director of the Yale cancer Center.

The 2004 Surgeon General's report adds more evidence to previous conclusions that smoking causes cancers of the oral cavity, pharynx, larynx, esophagus, lung and bladder.

Those first few puffs on a cigarette can within minutes cause genetic damage linked to cancer, us scientists said in a study released Saturday.