Reproductive and hormonal risk factors of breast cancer: a historical perspective

Abstract

Julie Horn,1,2 Lars J Vatten1 1Department of Public Health and Nursing, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway; 2Department of Gynecology and Obstetrics, Levanger Hospital, Nord-Trøndelag Hospital Trust, Levanger, Norway Abstract: The complexity of breast cancer etiology has puzzled scientists for more than 300 years. In this brief review, we emphasize the importance of reproductive and hormonal factors in relation to the risk of breast cancer. By following the historical course of how various risk factors have been determined, this study attempts to illustrate the origin of hypotheses, their subsequent rejection, and development of new hypotheses. Starting with the contributions of Italian physicians in the 18th century and covering the activity of British epidemiologists before World War II, this review ends up with the international collaboration that became increasingly important in the second half of the 20th century. Keywords: age at first birth, epidemiology, estrogen, lactation, parity, pregnancy

Keywords

• Breast cancer
• epidemiology
• risk
• reproductive factors
• hormonal therapy