How does smoking tobacco increase the chances of cancer?

Carcinogens: Tobacco contains a number of chemicals that can damage dna and promote growth. This combination is conducive to cancer formation in genetically susceptible people.

Greatly. Both: To the smoker and those inhaling the sidestream smoke. It has carcinogens. It causes >90% lung cancer, associated with h&n, pancreas, bladder cancer. Also destructive lung disease and heard and vascular disease. Epidemiologists claim smoking to age 35 will cause death in 50% of those exercising the freedom to smoke.