Epidemiological Clues in Breast Cancer

Abstract

A lot of speculation has been done on the endocrinology of breast cancer. There are however 3 interesting leads. The 1st is the attempt by Cole and MacMahon in 1969 to interpret the results of an impressive epidemiological study in endocrinological terms; the 2nd is the finding that endocrine abnormalities precede the clinical appearance of the disease and the 3rd is that there is now strong presumptive evidence that a virus is the initiating agent in man. 1 of the most important findings in recent years is the demonstration by MacMahon in 1970 that women who have pregnancies early in their reproductive life have a marked reduction in lifelong risk of breast cancer compared with that of women having their 1st pregnancies after 35 years. Then in 1961 Guernsey found that low androgen excretion might be a factor in preclinical stages of the disease. Warren found that the earlier chronic mastitis was found the greater the risk of subsequent breast cancer. These findings can all be integrated but in terms of the total endocrine status of the women at high risk they can only be speculative. Direct measurements of plasma estrogen progesterone and prolactin are now required. Another point of endocrinology is that hormones are not initiators of transformation of normal breast cells into malignant ones. An initiating agency such as the mammary tumor virus is required. Virus may be the initiating agent in man but endorine status may be the determinant of whether or not a tumor develop s. New assays for most of the important hormones and new methods for de tecting mammary tumor virus are needed.