Oral contraceptives and cancer.

Concerns over the safety of oral contraceptives (OCs) have led to numerous empirical studies of the relationship of OC use to normal pregnancy outcomes pituitary effects cardiovascular accidents and cancer. The article reviews some of the results of studies on the effects of OC use on ovarian uterine cervical and breast cancer and on hepatic cancer and melanomas. Reference is made to direct study results rather than to reviews of studies although it is noted that the critical reviews of Goldzieher and Realini reflect appropriate critiques of the validity of the methods employed in the analysis of cancers as well as cardiovascular risks. Concern is raised for meta-analysis of pooled data. In spite of the 30 years of research on OCs there is no definitive answer to the question of cause and effect. The epidemiological articles reviewed do not meet the standards of critical editorial review boards of experimental journals; confirmation of findings is also lacking. Studies suggesting increased risks as well as those showing positive benefits are questionable. The conclusion reached is that OCs protect against ovarian and uterine cancers and do not cause mammary cervical or liver cancer or melanoma. This conclusion is based on inconclusive data. The conclusion on hepatic cancer is that the 3 retrospective case control studies and anecdotal reports are flawed in design and little confidence can be placed on such a limited number of cases. Malignant melanoma conclusions are that the data are inconsistent and hover around a risk of one for long-term OC-users. There is no increased risk related to OC-use. Ovarian cancer risk seems to be decreased in about 40% of OC-users. Endometrial cancer risk seems to be decreased except for the sequential contraceptive Oracon which is associated with increased risk. Decreased risk is related to length of usage and continues after stoppage. Cervical carcinoma results appear to confirm the finding that prolonged OC use slightly increases the risk but confounding factors may be present. Breast cancer shows no association with OC use but inconsistent data among subgroups particularly young women who used OCs before their first birth some increased risks show.