Neoplastic effects of oral contraceptives
Grimes, D.A.
International Journal of Fertility 36(Suppl 1): 19-24
1991
ISSN/ISBN: 0020-725X PMID: 1678377 Document Number: 316451
Since hormones relate to the etiology of breast cancer, 40 studies have looked at the possible association of oral contraceptives (OCs) with breast cancer. Most research conducted through 1986 and including the largest related case control study and several after 1986 found no association between ever use of OCs and breast cancer. On the other hand, some studies conducted after 1986 with women 45 years old who had breast cancer and had taken OCs have suggested a dose response relationship, 2 fold increased risk of breast cancer, or increased risk with duration of OC use. These results motivated several organizations to review the literature and to issue guidelines. The US Food and Drug Administration, the UK Committee on the Safety of Medicines, and IPPF did not find a reason to change practices. The Committee on the Safety of Medicines did suggest, however, that health providers mention the possible increase in risk. At least 8 studies have revealed an increased risk of cervical cancer with duration of OC use, especially after 5 years of use. Yet experience has disclosed an obstacle to understanding the relationship between cervical cancer and OC use--cervical cancer may be caused by the human papilloma virus transmitted by sexual intercourse. Unlike results of breast and cervical cancer research, research results have clearly established that OC use lowers the risk of endometrial cancer by about 50% and the risk of ovarian cancer by about 40%. In fact, the US Cancer and Steroid Hormone [CASH] study showed a protective effect of OCs for endometrial and ovarian cancers at least 15 years after discontinuation. Even though some studies found a dose response effect with duration of use, a large international study did not find any relationship between OC us and liver cancer. Moreover studies did not reveal an association between OC use and malignant melanoma or pituitary adenoma.