Monthly combined injectable contraceptives and neoplasia.

Monthly injectable contraceptives, containing a combination of a long-acting progestogen and an estrogen, have been used in Latin America and China for many years. While knowledge about the effects of other hormonal contraceptives on cancer risk is relevant, close analogies with monthly injectables cannot be made. The relation between use of these preparations and cancers of the breast and cervix has been examined in case-control studies, but no firm conclusions can be drawn because of limitations in sample size. Adequate studies of the influence of monthly injectable contraceptives on risk of neoplasia need to be carried out.