The risks and benefits of oral contraceptives
Brown, K.H.; Hammond, C.B.
Advances in Internal Medicine 34: 285-305
1989
ISSN/ISBN: 0065-2822 PMID: 2644761 Document Number: 369242
The risks and benefits of using oral contraceptives are reviewed critically, considering only large controlled, statistically sound studies. Generally insufficient time has elapsed to evaluate the current generation of low dose combined and triphasic pills. The most salutary effect of oral contraceptives is an approximate 60% reduced risk for ovarian cancer, the leading gynecologic neoplasm, invariably fatal. Endometrial cancer risk is cut by about half. Both ovarian and endometrial cancer risk reduction persists after discontinuation. Pills reduce the incidence of benign fibrocystic and fibroadenomatous breast disease, avoiding about 20,000 hospitalizations yearly. Also numbers of functional ovarian cysts are reduced in pill users, eliminating about 3000 major hospitalizations annually. Pills reduce risk of pelvic infection of 10-70%, thereby lowering the potential for ectopic pregnancy: about 10,000 hospitalizations for ectopic pregnancy are said to be prevented. In contrast, pills do modestly increase the risk of developing idiopathic venous thromboembolism, by about 2.8-fold, as estimated in 1985. Due to recent reductions in steroid doses, the statistics on thromboembolism will probably improve. Pills also cause mild elevations in blood pressure, about 4 mm Hg systolic and 1 mm Hg diastolic, in 1,5% of users, which resolve on discontinuation. There are inconsistent results from studies on chance of strokes in pill users. Studies on heart attack find increased risk largely confined to smoker and older women, up to 34-fold higher risk to heavy smokers over 40. Generally in young healthy women, risk of heart attack is less than that in term pregnancy. Although there are some indications of increased breast cancer risk in some subgroups of women, most recent large studies find no association. Similarly, certain women are at increased risk of cervical cancer while using pills, although the specific risk factors have not been delineated. The risk of liver tumors is enhanced statistically, but the absolute numbers of cases are so low as to be unmeasurable. No sound evidence now exists for heightened risk of pituitary tumors or malignant melanoma.