This is the fourth book in a series dealing with breast cancer. Volumes 1-3 were concerned with treatment, experimental biology, and a number of varied timely topics. The present volume continues to review the breast cancer field in the broadest sense. The first chapter addresses the question of selecting appropriate chemotherapy for the patient. In the 1970s, great advances were seen in our ability to achieve objective tumor regression with empirical combina­ tions of chemotherapeutic agents. The next decade will focus on precise methods to select those agents likely to have the greatest benefit in individual patients. Livingston has provided us with a thorough review of the current state of the art. We have known for some time that steroid hormone receptor assays of considerable value to clinicians caring for patients with advanced disease. Osborne and colleagues now present considerable arguments that receptor assays are also useful in the setting of primary breast cancer for purposes of both prognosis and treatment strategy. A very important clinical problem which has received little attention in the research laboratory is benign breast disease. If one inquires about the medical therapy of this disorder in the United States, it is obvious that the majority of physicians would appreciate a better understanding of the pathophysiology which might lead to improved therapies. Mauvais-Jarvis and co-workers provide us with such an account from their wide experience.