Abstract

Substantial evidence exists to suggest that the use of oral contraceptives alters the risk for some types of cancer. Use of oral contraceptives for one year or more will reduce the risk of endometrial cancer and epithelial ovarian cancer by 50%, with the protective effect lasting for at least 10 years. The risk for developing cervical cancer in women who have used oral contraceptives appears to be slightly increased, although two independent studies actually found a protective effect associated with oral contraceptive use. The protective effect was probably related to the increased screening frequency found in oral contraceptive users and not related to a biologically protective effect. Therefore, women should be encouraged to undergo regular Pap tests. Data regarding breast cancer, in general, show no increased risk associated with oral contraceptive use. The latency associated with the development of breast cancer does not allow a definitive conclusion, and further study will be required. Oral contraceptives appear to increase the risk for developing benign hepatocellular adenoma, but not hepatocellular carcinoma.

PIP:

A review of the risk of endometrial, ovarian, cervical and breast cancer in oral contraceptive users sets these neoplasms in perspective. Endometrial cancer is the 3rd most common cancer in U.S. women with 34,000 cases annually. The average women is 61 years old. Risk factors are obesity, nulliparity, late menopause and unopposed estrogens. Oral contraception for 1 year or more reduces the risk of endometrial cancer as much as 50%, more so for nulliparous women, and this protection lasts as long as 10 years. Ovarian cancer, with a 5-year survival of only 30%, kills 11,000 women a year. Risk factors are nulliparas, late 1st pregnancy and prior breast cancer. Orals decrease the risk as much as 50%, in proportion to duration of use. Cervical cancer, now only the 6th leading cause of cancer deaths for women because of screening, is probably a venereal disease. This complicates studies on the risk of pill use, which are controversial because of confounding factors such as sexual activity, surveillance, use of barrier contraceptives, and method of grading Pap test. Breast cancer has a long list of known risk factors, but studies linking the pill are controversial, especially regarding latency. The majority of studies report a relative risk around 1.0.