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Social factors in Cancer Etiology
Social class may show a gradient for factors such as education, housing, income and occupation. Stomach and cervical cancers are higher in lower socioeconomic groups, as is lung cancer. While the incidence of some cancers may be higher in this setting, smoking, occupational exposure and the unavailability of medical care are important. Breast and colorectal cancers, in contrast, are seen in those with high socioeconomic status.
Lifestyle factors operate through three settings. One is environment which determines exposure to radiation from medical and other sources with the attendant risk of leukemia, and also to risks from improper food handling, such as contamination by aflatoxins from moulds which are associated with liver cancer in Africa. Another is social habits which can determine exposure to physical, chemical and biological environmental agents. The third is the action of these specific agents on the human body - the biological aspects.
Occupational risks have been noted above. Among the first of these to be documented was scrotal cancer in chimney sweeps in England during the industrial revolution.
Medical services and care also bring their own risks. Chest fluoroscopy that used to be done for tuberculosis was found to be associated with a risk for breast cancer. The chemotherapeutic agents used to treat cancer are themselves carcinogenic. Concern is being expressed about the use of estrogens for menopausal symptoms and risk for endometrial and breast cancers.
Air and water pollution are of comparatively minor importance as risks for cancer. Both ground and surface water can be polluted. Automobiles as well as industrial and hazardous wastes all contribute to the problem.
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