A current perspective on genetic testing for breast and ovarian cancer: the oral contraceptive decision.

A clinician faces a problem in how best to counsel the woman with a family history of breast or ovarian cancer about her options for pregnancy prevention. The physician must guide her as she makes new and complex decisions. Recent data strongly support an amplified effect of the estrogens in oral contraceptives for the woman with a genetic risk for breast cancer. Nonetheless, a woman's immediate need to prevent pregnancy may be much more important to her than worrying about the long-term risk of breast cancer. Another factor is that oral contraceptives prevent ovarian cancer, so the physician may wish to prescribe them to protect her from ovarian cancer. In some genetic backgrounds, however, oral contraceptives not only do not prevent ovarian cancer, but they may raise the risk of breast cancer so significantly that they should not be taken. With other genetic backgrounds, oral contraceptives will protect the woman from ovarian cancer without much effect on her breast cancer risk. When does each of these cancer risks or benefits become significant? The clinician can provide an important benefit to a woman who must prevent pregnancy yet worries about her cancer risk. The physician can help her evaluate the evidence, with its gaps and uncertainties, in the context of her own preferences. To assist in this evaluation, this decision aid provides base-line estimates of the cancer risk that accompanies each of a woman's options. In some cases, genetic testing is likely to provide valuable information as she makes choices about contraception and the risks vs. benefits of different alternatives available to her.