front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |21 |22 |23 |24 |25 |26 |27 |28 |29 |30 |review

Because of the widespread nature of the tobacco habit, control of carcinogenesis by chemical agents provides a major basis for cancer control. The process of carcinogenesis by chemicals is subject to both initiation and promotion steps. These carcinogens have a particular chemistry as aromatic electrophiles - chemically very reactive substances often formed as metabolic products. * Some have medicinal sources, such as the use of diethylstilbestrol in pregnancy to avert abortion resulting in vaginal cancer in the daughters. * Others come from habits such as the use of tobacco (oral and lung cancer, and other tumors) or alcohol (head and neck cancers). * Industrial and occupational exposures are also important: