The main way that smoking causes cancer is by damaging our DNA, including key genes that protect us against cancer. Many of the chemicals found in cigarettes have been shown to cause DNA damage, including benzene, polonium-210, benzo(a)pyrene and nitrosamines.
This is already bad news, but it’s made worse by other chemicals in cigarettes. For example chromium makes poisons like benzo(a)pyrene stick more strongly to DNA, increasing the chances of serious damage. And chemicals like arsenic and nickel interfere with pathways for repairing damaged DNA. This makes it even more likely that damaged cells will eventually turn cancerous.
Smokers are also less able to handle toxic chemicals than those with healthy lungs and blood. Chemicals in cigarette smoke make it harder for smokers to neutralist or remove toxins, and can make their immune systems less effective too......
It usually takes many years, or decades, for the DNA damage from smoking to cause cancer. Our bodies are designed to deal with a bit of damage but it’s hard for the body to cope with the number of harmful chemicals in tobacco smoke. Each cigarette can damage DNA in many lung cells, but it is the build up of damage in the same cell that can lead to cancer. However research has shown that for every 15 cigarettes smoked there is a DNA change which could cause a cell to become cancerous. This is why it’s better to give up smoking sooner rather than later.
I get this information from Google. You can get more in there.
