Cancer and the environment

It has been estimated that 80–90% of cancer in man is determined by his environment. The problem is reviewed with reference to the natural external environment — sunlight, air, food and water, and to the cancers which are the result of known pollutants, whether these be general or occupational. There are other aspects of the external environment which are under individual control. “Cultural” cancers, such as lung cancer from cigarette smoking, can be completely abolished. “Therapeutic” cancers from diagnostic and remedial medicine are under surveillance. The contribution to cancer morbidity of man's internal environment is hard to assess and difficult to alter. Single factors only can be isolated in animal experiments. Man, himself, is subject to complex interactions between multiple external factors and an internal environment which may be more or less aberrant. Almost nothing is known about such interactions. Cleaning the environment can lead to fast results in reducing cancer morbidity. Quicker progress might be made if known procedures for diagnosing the disease are applied more vigorously to high‐risk populations and if new methods are sought for readily distinguishing these groups.