PIP: Women often are worried that oral contraceptives (OCs) increase the risk of developing cancer. Physicians should inform women seeking a contraceptive method of the relationship between OC use and lower reproductive tract cancers. The overall relative risk of ovarian cancer is reduced in OC users by 36-40%. The risk declines with duration of OC use (e.g., 50% reduction for = or 5 years, 80% reduction for = or 10 years). OC use provides protection against ovarian cancer for at least 10 years after OC discontinuation. The studies so far have been limited to monophasic OCs, but low-dose triphasic OCs probably afford the same protection. The biologic mechanism for protection against ovarian cancer may be that OCs suppress both ovulation and pituitary gonadotropin levels. OCs reduce the risk of endometrial cancer and the effect is time-dependent. 12-23 months of OC use reduces the risk 40%, while at least 10 years of OC use reduces the risk 60%. The protective effect emerges within 10 years of first use. OCs likely reduce the risk of endometrial cancer by decreasing estrogenic proliferation and increasing exposure to progestogen. It is hard to interpret the results of epidemiologic studies on OC use and cervical cancer because of confounding factors (e.g., number of sexual partners) are not taken into consideration. Evidence is rising, however, that OCs may increase the risk of cervical cancer. Thus, physicians should conduct at least annual Pap smear screening for OC users, particularly if they have used OCs for more than 5 years.