Comparative aspects of contraceptive steroids: effects observed in the monkey

The use of the non-human primate in long-term studies of contraceptive steroids has been questioned because of time, expense and apparent lack of results predictive for humans. Controversies have arisen primarily over the occurrence of mammary nodules in studies of different contraceptive steroids and the occurrence of uterine tumors in 2 high-dose group monkeys in the Depo-Provera study. The long-term studies have been criticized because of the experimental design and the small number of monkeys per dose group. Individual studies by themselves did not reveal lesions other than those expected from an exaggerated pharmacologic response of target tissues; however, a pattern may emerge from reviewing and combining results of different studies that indicate the results of these studies are in agreement with the clinical findings in man. Effects of contraceptive steroids on the mammary gland and genital organs will be discussed. Data from 17 contraceptive steroid studies involving 264 untreated control and 733 treated non-human primates were available.