This is what happens with the use of tobacco. In addition to the mutagens in cigarette smoke there are irritants that are inhaled through the mouth, down the throat and into the lungs, wounding and killing cells on a long-term basis. Healthy cells fight the chronic irritation by dividing, creating new cells to replace those that are dead or too damaged to do their work. For many cigarette smokers, the fatal conclusion of cell proliferation is lung cancer. Injury to the lips of pipe smokers can also lead to skin cancer.
Liver cancer provides another interesting example of what incessant irritation can cause.
The incidence of this form of cancer is low in humans, unless the liver has been damaged by alcohol excess or chronic infection by the hepatitis B virus. Thanks to MTD testing, newspapers always have another cancer threat to write about. Most often, the finger of suspicion points accusingly at synthetic pesticides. They think they can bypass danger by only consuming foods that are free of synthetic pesticides. This strategy doesn't work either.