Quitting smoking substantially reduces the risk of developing and dying from cancer, and this benefit increases the longer a person remains smoke free.
However, even after many years of not smoking, the risk of lung cancer in former smokers remains higher than in people who have never smoked.
The risk of premature death and the chance of developing cancer due to cigarettes depend on the number of years of smoking, the number of cigarettes smoked per day, the age at which smoking began, and the presence or absence of illness at the time of quitting.
For people who have already developed cancer, quitting smoking reduces the risk of developing a second cancer.
It is not how many years we live, but what we do with them. Health Service Food and Human Resources: Discount Cigarettes Brands