A reprint of the 1989 edition of this book has been made necessary by continuing demand after rapid exhaustion of the first printing. In the two years since its appearance, there has been relatively little expansion of knowledge on this topic, and its massive accumulation of references still remains an authoritative guide in the difficult task of developing a national breast cancer prevention model. At the same time, its thesis has been sharpened by the publication of a companion volume Approaches to Breast Cancer Prevention (Kluwer, 1991) similarly edited byrne. Breast cancer is on the increase throughout the Western world where it is a major source of anxiety among women. The disease is also becoming more frequent in Asian and South American countries where once it was relatively uncommon. Multiple fac- tors are suspected of promoting the disease and the increasing risk is attributed to recent changes in life-style and diet. This book is intended to provide an authorita- tive and balanced survey of the latest research into the genetic, familial, hormonal, reproductive, nutritional, social and geographic factors known to be associated with an increased predisposition to the disease.