More than 8 million people die each year from smoking, and smoking is the cause of about 90 percent of all lung cancer cases. Researchers estimate that smokers are 15 to 30 percent more likely to develop lung cancer than non-smokers.
The carcinogens damage the lung cells and cause mutations in the DNA. Genetic research has shown that the lung cells of smokers who devour a pack a day develop as many as 150 new mutations in a year.
These mutations can cause unusual behavior in the lung cells and uncontrolled cell division, which can lead to cancer. The number of mutations in the lung cells is closely related to how much a person smokes. That is why the risk of lung cancer increases the more people smoke.
Chain smokers can repair DNA damage better
But according to a new study, the number of new mutations is no longer rising in persistent smokers who smoke a pack a day for more than 23 years. And that may explain why some chain smokers smoke for a lifetime without developing lung cancer.
The lung cells seem to adapt to the constant presence of tobacco smoke by better repairing DNA damage and removing the mutations.
The researchers now want to look at why the DNA can be repaired in some people, but not in others, because then it may be possible to determine at an early stage how high a person’s chance of developing lung cancer is.