For example, although alkylating chemotherapeutic drugs are potent carcinogens in various animals, withholding them from a patient with a potentially lethal disease is illogical. The situation is analogous to exposure to x-rays, which also may be carcinogenic. Very few drugs for which there is convincing evidence of carcinogenesis in humans are used. Rarely, oral contraceptives appear to cause hepatic adenomas, whose growth is benign but which are extremely vascular and can cause fatal hemorrhage. Reserpine has been associated with breast cancer in case-control studies, but the association has not been confirmed in cohort studies.
Convincing evidence suggests that some nondrug chemicals are carcinogens.
The evidence includes an association between aflatoxins and hepatoma, vinyl chloride and liver hemangiosarcoma, coal tars and skin cancer, cigarette smoke and lung cancer, and aniline dyes and bladder tumors. All rights reserved.