What are the reproductive risk factors for ovarian cancer?

Updated: Aug 10, 2020
  • Author: Andrew E Green, MD; Chief Editor: Yukio Sonoda, MD  more...
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Parity is an important risk factor. The risk of epithelial ovarian cancer is increased in women who have not had children and possibly those with early menarche or late menopause. Women who have been pregnant have a 50% decreased risk for developing ovarian cancer compared with nulliparous women. Multiple pregnancies offer an increasingly protective effect. Oral contraceptive use decreases the risk of ovarian cancer significantly.

These factors support the idea that risk for ovarian cancer is related to ovulation. Two theories regarding this relationship have been proposed. The incessant ovulation theory suggests that repeated ovarian epithelial trauma caused by follicular rupture and subsequent epithelial repair results in genetic alterations within the surface epithelium. The gonadotropin theory proposes that persistent stimulation of the ovaries by gonadotropins, coupled with local effects of endogenous hormones, increases surface epithelial proliferation and subsequent mitotic activity.

Thus, the probability of ovarian cancer may be related to the number of ovulatory cycles, and conditions that suppress the ovulatory cycle may play a protective role. Ovulation suppression has been shown to decrease cancer incidence. Although treatment with agents that induce ovulation in women with infertility has been suggested to increase the incidence of epithelial ovarian cancer, this is unproven.

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