LONDON – Scientists have found that smoking a pack a day of cigarettes can cause 150 damaging changes to a smoker's lung cells each year.
The findings come from a study of the devastating genetic damage, or mutations, caused by smoking in various organs in the body.
Publishing in the journal Science on Thursday, the researchers said the findings show a direct link between the number of cigarettes smoked in a lifetime and the number of mutations in the DNA of cancerous tumors.
The highest mutation rates were seen in lung cancers, but tumors in other parts of the body - including the bladder, liver and throat - also had smoking-associated mutations, they said. This explains why smoking also causes many other types of cancer beside lung cancer.
Smoking kills six million people a year worldwide and, if current trends continue, the World Health Organization predicts more than 1 billion tobacco-related deaths this century.