Prevention of cancer: practical prospects

The discovery of some 40 specific factors that have caused cancer in humans has demonstrated conclusively that many fatal cancers are capable of being prevented. These known factors are responsible for less than half all fatal cancers in all countries and much less in most; but there is good evidence, derived from the variation in the incidence of cancer in different communities, in different countries, and at different times that in many countries it may be possible to prevent 80% of all cancers or even more. The practical problems facing each country are different. Not only are the types of cancer different that need most urgently to be prevented, but so are the social and economic conditions that permit or constrain the introduction of preventive measures. Well-understood measures are summarized and the prospects for others that are less established or as yet untried are discussed, including the use of low-tar cigarettes, dietary modification, and anti-viral vaccines.