Obesity and cancer. A review of epidemiological studies on the relationship of obesity to cancer of the colon, rectum, prostate, breast, ovaries, and endometrium.

Cancer of the colon, rectum, prostate, breast, ovaries and endometrium may be associated with obesity. The present paper reviews both prospective and retrospective studies of the potential associations between obesity and these cancers. This research is especially difficult because of the complex interrelations between weight and diet, physical activity, cigarette smoking, and other conditions. Epidemiological studies of body weight are subject not only to biases of sampling, selection, and confounding but also to marked difficulties in definition and measurement. Bearing in mind the methodological shortcomings, there is a distinct and reproducible association between obesity and cancer of the endometrium and postmenopausal breast cancer. The studies of cancer of the colon, rectum, prostate, and ovaries are too inconclusive to elucidate whether obesity implies an increased risk. It is recommended that future studies in this field include a standardised assessment of the distribution of fat tissue, the onset and duration of the condition, and the associated confounding factors. It is concluded that obesity, especially in females, should be avoided as a part of the general cancer preventive effort.