Smoking contains thousands of chemicals and about 60 of them are carcinogens or cancer-causing agents that can damage DNA. DNA is the code that tells a cell what to do. When the DNA is damaged, a cell might start to reproduce in an uncontrolled way and even spread throughout the body destroying it. That’s cancer. It takes time for the damage to reach a turning point—to become so severe that cancer results. It could be just a few years in some; it might take 40 years in others. The good news is that no matter how long you have been smoking, once you stop the DNA in your cells gets to work on making repairs and your risk of cancer will go down dramatically.
In just 5 years, your risk of mouth, throat, esophageal, and bladder cancer have been cut in half. You will heal. Your risk of developing lung cancer may never match that of people who never smoked but instead of your risk rising with every cigarette, it will plummet with each year you are smoke free. Other cancers less likely to occur after you quit include head & neck cancers (mouth, nose, throat, etc.), cancer of the stomach, pancreas, liver, kidney and cervix.
There is a Memorial Sloan Kettering tool to help older people (aged 50 to 75), who have smoked at least a half of a pack/day for at least 25 years and are either still smokers or quit within the past 20 years, estimate their risk of lung cancer.
The bottom line is quit as early as possible and get screened for lung cancer if you have not quit or have been a smoker. It will save lives.
This information is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment, and should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.