Why does the risk of cancer diminish rapidly after one quits the cigarette smoking habit?
The development of a cancer cell, also called a malignant cell, requires both an initiator and a promoter. An initiator is an agent that begins to alter a cell, transforming it into a premalignant state. A promoter is an agent that converts the cell to a irreversible malignant state. Promotion is a slow process, which requires repeated exposure to the promoter. Tobacco smoke contains both initiators and promoters, which is why the risk of cancer diminishes rapidly after one quits smoking. Source: Zakrzewski, Sigmund F. Principles of Environmental Toxicology, p. 69.
