Women who take birth control pills cut their risk of ovarian cancer in half, possibly because these drugs prevent ovulation. (Ovulation is the release of an egg from the ovary each month.) The protective effect of the pill is greatest in women who use it for four years or longer. Breast-feeding, which also reduces the number of times a woman ovulates, may trim the risk of ovarian cancer.
Women who know that they carry the BRCA1 or BRCA2 gene might consider having their ovaries removed before cancer develops.