Causes of Ovarian Cancer

The causes of ovarian cancer are unclear, but genetic and endocrine factors raise the risk. The most significant cause is a positive family history, which is present in 10% of women with the disease. Three hereditary syndromes in which ovarian cancer occurs more commonly affect certain families with a history of early breast and ovarian malignancies and hereditary nonpolyposis colorectal cancer.

Other causes associated with ovarian cancer include nulliparity, giving birth for the first time when over age 35, exposure to talc or asbestos, endometriosis, pelvic inflammatory disease, and living in a western industrialized country.

On the bright side, researchers have identified seemingly protective factors, including a history of oral contraceptive use, giving birth before age 25, tubal ligation, breast-feeding, and hysterectomy.

Most commonly, ovarian cancer spreads via the peritoneal fluid that continuously circulates through the abdomen. Other routes for metastases are through the lymphatic fluid or by direct tumor extension. Bloodborne metastasis is rare, and this cancer rarely spreads beyond the abdomen, even when advanced.

The incessant-ovulation theory zeroes in on how the monthly ovulatory cycle affects the ovaries. This theory holds that the epithelium may be more apt to mutate with each ovulation, so failure to break the cycle, as with pregnancy, increases the chance of mutation.

The pituitary/gonadotropin hypothesis implicates elevated gonadotropin levels. Normally, the ovarian epithelium invaginates and forms inclusion cysts and clefts, but overstimulation by gonadotropins might trigger proliferation with subsequent malignant transformation.

The inflammation theory considers monthly ovulation a possible cause of chronic inflammation and mutation in the epithelial cells that lead to ovarian cancer.

Last updated Nov 26/06