propose one mechanism by which smoking cigarettes causes cancer?

Question

cigarettes smoke is mostly oxygen, CO2 and nitrogen. The rest contains at least fifty five different chemicals identified as cancerogenic. When these cancerogenic enter the bloodstream, enzymes convert them to a series of chemicals that are easier to excrete. Therefore do you know one mechanism by which smoking cigarettes causes cancer?
Please answer only if you know the right answer.
Thank you very much.

Answer 1

Many of them don't get that far. They come out of the inhaled smoke and deposit on the air sacs of the lungs. They don't need to get into the blood stream - they can cause COPD from right there.