Ovarian Cancer - Causes

Gonadotropins and Fertility Drugs. Gonadotropins are hormones produced in the pituitary gland that stimulate the ovaries to secrete estrogen and cause the follicles to produce and release eggs.

The pituitary is a gland attached to the base of the brain which secretes hormones that govern the onset of puberty, sexual development and reproductive function.

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In a few studies, elevated levels of gonadotropins have been associated with an increased risk for ovarian cancer. These hormones are the basis for many fertility drugs, including human menopausal gonadotropin (Pergonal, Repronal, Metrodin) and clomiphene (Clomid, Serophene). Although there has been concern about an increased risk for ovarian cancers in women, a growing body of evidence is finding no higher risk from the drugs themselves. Instead, evidence suggest that ovarian cancers are most likely caused by factors contributing to the infertility -- not the agents used to treat it.

Hormone Replacement Therapy (HRT). Although some studies have reported a weak increased risk for certain ovarian cancers in women taking HRT, others have found no association either with short- or long-term use of HRT.

Inherited Genetic Factors

Family history plays a role in between 5% and 10% of women who have ovarian cancer. Certain genes are being investigated and identified that are responsible for some of these cases. Depending on the particularly genetic type, the lifetime risk for ovarian cancer in women who carry these genes ranges from 16% to 65%.

BRCA1 and 2 Genes. Inherited mutations in genes known as BRCA1 or BRCA2 are now believed to be responsible for 30% to 50% of breast cancers, ovarian cancers, or both in patients with a strong family history of these cancers.

According to some studies, the risk each carries appears to be as follows:

Studies indicate that about 25% to 40% of women who carry the abnormal BRCA1 gene may develop ovarian cancer.
The risk for women with the BRCA2 gene mutation is generally believed to be lower, about 9% to 15%.

The mutated genes are linked to an even higher risk for developing breast cancer. These mutations are present in only about 0.5 of the US or UK population overall but occur in about 2.5% of all Jewish women of Eastern European (Ashkenazi) descent. This prevalence in a relatively large population makes mutations to BRCA1 and BRCA2 the most common serious genetic disease known in any population group. These mutations are not restricted to the Ashkenazi population and may occur in women of any ethnicity, including women of Asian and African descent.