This volume contains the proceedings of the Third International Symposium on Hormonal Carcinogenesis held September 6-12, 1998, in Seattle, Washington. It is clear that breast and prostate cancers are by far the most common cancers in developed countries and have similar incidences worldwide. Endometrial and ovarian cancers also occur at relatively high frequencies in women. Sex hormones have emerged as major culprits in the development of these neoplasms. This Symposium brings together basic scientists, epidemiologists, and clinicians from a wide range of disciplines to present the latest research developments aimed to elucidate the involvement of hormones in the etiology, promotion, and progression in neoplastic transformation of target tissues as well as their prevention. Therapeutic indices related to these hormonally-related cancers is also presented, including benefits and risks.