Oral contraceptive use and the risk of ovarian cancer. The Centers for Disease Control Cancer and Steroid Hormone Study
Since oral contraceptives have been used by more than 40 million American
women, an association between oral contraceptives and ovarian cancer could
have a substantial public health impact. The Centers for Disease Control,
Atlanta, is studying this relationship as part of a multicenter,
case-control study--the Cancer and Steroid Hormone Study. During the first
ten months of the study, we enrolled 179 women aged 20 to 54 years who had
been ascertained to have newly diagnosed ovarian cancer by eight
population-based cancer registries. From the general population of those
eight areas, we selected as controls 1,642 women with intact ovaries. Users
of oral contraceptives had an age-adjusted risk of ovarian cancer
developing of 0.6 relative to those who had never used them (95% confidence
interval, 0.4 to 0.9). The risk of ovarian cancer decreased with increasing
duration of oral contraceptive use and remained low long after cessation of
use. These results were not accounted for by parity, infertility, or other
potentially confounding factors. We estimate that more than 1,700 cases of
ovarian cancer are averted each year by past and current oral contraceptive
use among women in the United States.
