Observations of relevance to understanding the etiology of breast cancer have been made recently both by endocrinologists and by epidemiologists. Generally speaking, investigators in these 2 disciplines have worked in ignorance of the contributions of the other field. When the observations from the 2 fields are considered together, useful hypotheses, and surprising gaps in our knowledge, are identified. I n this paper we attempt to integrate knowledge from the 2 fields, specifically to explore 3 issues: 1. which endocrine organ is most directly involved in etiology, 2. what special characteristic of that organ's function is associated with breast cancer risk, and 3. what are the determinants of that special characteristic.
LMOST WITHOUT EXCEPTION, WRITERS ON
A the causes of breast cancer have acknowledged the major significance of endocrine factors. Yet there is little agreement as to which hormonal patterns, or even which endocrine organs, are most relevant. Certainly, no findings with real preventive implications have been forthcoming. Success in uncovering such findings would seem most likely to come from attempts to evaluate basic endocrinologic knowledge in the light of observations on the behavior of the disease in man.
Although the descriptive epidemiology of breast cancer is as complete as that for any other cancer, and a wealth of information exists on the response of the breast to hormones and carcinogenic compounds, few efforts to integrate these bodies of knowledge have been made. I n the time available, we cannot attempt any comprehensive review along these lines. We plan only to draw together epidemiologic and endocrinologic evidence on 3 basic questions: 1. which endocrine organ is most directly involved in etiology, 2. what special characteristic of that organ's function is associated with breast cancer risk, and 3. what are the determinants of that special characteristic.