Experts don’t get tired of reminding us that smoking causes numerous diseases, like stroke, heart diseases, and cancer. According to the US National Institute of Cancer, smoking leads to cancers of the mouth, larynx, esophagus, lung, kidney, bladder, pancreas liver, stomach, cervix, colon, and rectum. But how exactly does smoking result in the “big C”? And another thing: how many cigarettes cause cancer? Find out here.