As parity is inversely related to the risk of ovarian cancer, having at least one child is protective of the disease with a risk reduction of 0.3to 0.4. Remarkably, use of oral contraceptives for 5 or more years reduces their relative risk to 0.5, ie (there is a 50% reduction in the likelihood of developing ovarian cancer). Women who have had two children and have used oral contraceptives for 5 or more years have a relative risk of ovarian cancer as low as 0.3, or a 70% reduction. Therefore, the oral contraceptive pill is the only documented method of chemoprevention for ovarian cancer, and it should be recommended to women for this purpose. When counseling patients regarding birth control options, this important benefit of oral contraceptive use should be emphasized. This is also important for women with a strong family history of ovarian cancer.

Fenretinide
Fenretinide (4-hydroxyphenyl-all-trans-retinoic acid amide), a vitamin A derivative, has been given to women with unilateral breast cancer in an effort to reduce the risk of contralateral breast cancer. In a prospective, randomized, placebo-controlled trial conducted in Italy, women with unilateral breast cancer were given either oral fenretinide or a placebo for five years. In the treatment group, no ovarian cancers developed during the five years on study, whereas there were 6 cases of ovarian cancer in the control group (p < .01). When participants were followed long-term, however, the protective effect disappeared after discontinuing the drug. In cell culture, fenretinide can induce apoptosis in ovarian cancer cells and in normal ovarian surface epithelial cells. Trials are planned in the United States to determine the effect of fenretinide on the ovaries of women at high risk for developing ovarian cancer who will receive the drug prior to prophylactic oophorectomy.

Oophorectomy
The performance of a prophylactic oophorectomy will reduce, but not eliminate, the excess risk of cancer in women at high risk for developing ovarian cancer. Because the entire peritoneum is at risk, peritoneal carcinomas can occur even after prophylactic oophorectomy in less than 5% of cases. Because the ovaries provide protection from cardiovascular disease and osteoporosis, prophylactic oophorectomy should not be routinely performed in premenopausal women at average risk for ovarian cancer.