The epidemiology of breast cancer; Review and prospects

Abstract

In the epidemiology of a disease, which is multifactorial lo such an extent as we believe breast cancer to be, attention should be paid even to " In his review on the epidemiology of breast cancer, Lilienfeld (1963) made a plea for integrating laboratory investigations with epidemiological field studies. Six years later we are beginning to reach an era in which the epidemiologist turns to his friends in biochemistry (or they turn to him) in order to tackle this vast problem together. The task is vast indeed but not insoluble since we now have sufficient data on possible risk factors to undertake a number of prospective studies which will give us by, say, 1980, an insight into its aetiology, comparable to the knowledge which we have obtained over the past 20 years in coronary heart disease.The comparison with coronary heart disease is relevant in that laboratory studies in lipid metabolism have greatly helped us in understanding the interactions between environmental and " endogenous " factors, e.g. the effect of nutrition and exercise on blood cholesterol levels. In a similar way epidemiologists will have to venture into the field of endocrinology to advance their understanding of breast cancer. It will not be enough if they simply hand over a number of bottles of urine or some tubes with frozen plasma from cancer patients and controls to their biochemical colleagues. We shall have to learn more about the factors which might influence hormone patterns in normal women. Part of this knowledge has already been obtained by clinical endocrinologists, e.g. the effects of over-eating and starvation on adrenocortical hormone production and excretion; other aspects will arise through questions by epidemiologists.In the meantime, biochemists are introducing methods for the measurement of pituitary hormones in human body fluids. It will be of particular importance to develop a method for the estimation of human prolactin.What do we know? In human beings, as well as in other vertebrate species, possible aetiological factors in breast cancer development can be divided into four categories: 1) Hormonal factors; 2) Genetic factors; 3) Environmental factors;

Some observations on the epidemiology of cancer of the breast in women of Western India

“…However, in Japan and in most other Asian, African and Latin American countries, the incidence curve does not rise after the menopausal years, but levels off or even falls (De Waard, 1969). This has been the subject of much discussion for many years.…”

Breast cancer in black American women

“…Controls were Black women hospitalized for many other conditions and interviewed during the same time period. A woman with any malignant neoplasm or with a benign neoplasm of the breast or genital tract was excluded from the contro series.Since breast cancer may have a different etiology among pre-and postmenopausal women (DeWaard, 1969), results are reported separately for these groups, Premenopausal women were those aged 30-59 who were still menstruating when interviewed. Postmenopausal women were those aged 40-89 who reported having no menstrual period for at least 1 year before interview.…”

Oestrone sulphate, adipose tissue, and breast cancer

“…In the light of these considerations, some workers (44) consider that adipose tissue may have a special role in the aetiology of breast cancer, either by acting as a store for carcinogens, or perhaps by providing, via the enzymic mechanisms described above, a promoting, oestrogen environment. However, other workers (45) dispute such a special role for adipose tissue, and it is generally held that obesity, though possibly an indicator of poor prognosis in established disease (46), is not a strong risk factor for breast cancer (47)(48)(49)(50). Although obesity or total body fat may be unrelated to risk of breast cancer, it may still be that mammary fat content is of significance.…”