Oral contraceptives (OCs) are known to decrease a woman's risk of developing epithelial ovarian cancer. However, the dose of estrogens and progestins in OCs have come down in recent years so it is unclear if the protection previously offered still holds.
Lurie et al (Obstets Gynecol 2007;109:597-607) conducted a case-controlled study on over 700 women with epithelial ovarian cancer that took into account the woman's OC history and matched them with controls who may or may not have used OCs. Their results were conclusive. OCs were effective in decreasing the risk of cancer and the lowest formulations offered the strongest protection. The authors postulate that the antiovulatory mechanisms of OCs are the key factor in reducing malignancy rates and that women taking the lower dose pills are more likely to be compliant compared to high-dose users.
Consistency of use, rather than the hormonal dose probably explains the effect and a reduction in ovarian cancers may well continue due to OC use.
