This book provides an overview of the evidence from nearly 100 clinical trials in early breast cancer and presents conclusions aimed at helping all clinicians who treat women with this disease to select the best available therapy. Early breast cancer is diagnosed in several hundreds of thousands of women each year. If some widely practicable treatment could produce even a moderate reduction in the risk of death from the disease, this might avoid 10,000 deaths in a year and the unique world-wide collaboration of the EBCTCG has shown that this can be achieved.