Heather Spencer Feigelson Department of Epidemiology and Surveillance Research, American Cancer Society, Atlanta, Georgia, U.S.A.

Roberta McKean-Cowdin Norris Comprehensive Cancer Center, Keck School of Medicine, Los Angeles, California, U.S.A.

Neoplasia of hormone-responsive tissues currently accounts for more that 35% of all newly diagnosed cancers in men, and more than 40% of all newly diagnosed cancers in women in the United States (1). Bittner (2) first proposed the idea that hormones may play a role in the formation of cancer in studies of estrogens and mammary tumors in mice. Since that time, that theory has been refined and expanded with substantial and convincing evidence from experimental, clinical, and epidemiological studies. It is now generally recognized that hormones play an etiological role in cancers of the breast, prostate, ovary, endometrium, testis, thyroid, and bone.

This chapter will focus primarily on endogenous and exogenous sources of steroid hormones and their role in carcinogenesis of hormone-responsive tissue. Further, the chapter will review multigenic models that are being used to understand the etiology of breast and prostate cancers and that may serve as examples to establish new models for other hormone-dependent cancers.