But risk factors don't tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And many people who get the disease may not have had any known risk factors. Even if a person with ovarian cancer has a risk factor, it is very hard to know how much that risk factor may have contributed to the cancer. Researchers have discovered several specific factors that change a woman's likelihood of developing epithelial ovarian cancer. These risk factors do not apply to other less common types of ovarian cancer such as germ cell tumors and stromal tumors.

Age

The risk of developing ovarian cancer gets higher with age. Ovarian cancer is rare in women younger than 40. Most ovarian cancers develop after menopause. Half of all ovarian cancers are found in women over the age of 63.

Obesity

Various studies have looked at the relationship of obesity and ovarian cancer. Overall, it does seem that obese women (those with a body mass index of at least 30) do have a higher risk of developing ovarian cancer. A study from the American Cancer Society also found a higher rate of death from ovarian cancer in obese women. The risk was increased by 50% in the heaviest women.

Reproductive history

A woman who has had children has a lower risk of ovarian cancer than women who have no children. The risk gets even lower with each pregnancy. Breast feeding may lower the risk even further. Using oral contraceptives (also known as birth control pills or "the pill') also lowers the risk of ovarian cancer.

Gynecologic surgery

Tubal ligation (having your "tubes tied") may reduce the chance of developing ovarian cancer by up to 67%. A hysterectomy (removal of the uterus without removing the ovaries) also seems to reduce the risk of getting ovarian cancer by about one-third.

Fertility drugs

In some studies, researchers have found that using the fertility drug clomiphene citrate (ClomidŽ) for longer than one year may increase the risk for developing ovarian tumors. The risk seemed to be highest in women who did not get pregnant while on this drug. Fertility drugs seem to increase the risk of the type of ovarian tumors known as "low malignant potential" (LMP tumors). If you are taking fertility drugs, you should discuss the potential risks with your doctor. However, women who are infertile may be at higher risk (than fertile women) even if they do not use fertility drugs. This may be in part because they haven't had children or have not used birth control pills (which are protective). More research to clarify these relationships is now underway.

Androgens

Androgens are male hormones. Danazol increases androgen levels. A recent study found a link between the drug danazol (used to treat endometriosis) and an increased risk of ovarian cancer. Further studies are planned to look at this.

Estrogen replacement therapy and hormone replacement therapy

Some recent studies suggest women using estrogens after menopause have an increased risk of developing ovarian cancer. The risk seems to be higher in women taking estrogen alone (without progesterone) for many years (at least 5 or 10). The increased risk is less certain for women taking both estrogen and progesterone.

Family history of ovarian cancer, breast cancer, or colorectal cancer

Ovarian cancer can run in families. Your ovarian cancer risk is increased if your mother, sister, or daughter has (or has had) ovarian cancer. The younger your relative was when she developed ovarian cancer, the higher your risk. The risk also gets higher the more relatives you have with ovarian cancer. Increased risk for ovarian cancer does not have to come from your mother's side of the family - it can also come from your father's side. About 10% to 15% of ovarian cancers result from an inherited tendency to develop the disease. A family history of cancer caused by an inherited mutation (change) in certain genes can increase the risk of ovarian cancer. Some of these genes (named BRCA1 and BRCA2) also increase the risk of breast cancer - so having a family member with breast cancer can increase your risk of ovarian cancer. Another set of genes increase the risk of colon cancer, so women who have colon cancer in their families may have a higher risk of developing ovarian cancer. Many cases of familial epithelial ovarian cancer are caused by inherited gene mutations that can be identified by genetic testing.

Women with ovarian cancers caused by some of these inherited gene mutations may have a better outlook than patients who do not have any family history of ovarian cancer. (See the section on causes of ovarian cancer for information on these gene mutations.)

Genetic counseling, genetic testing, and strategies for preventing ovarian cancer in women with an increased familial risk are discussed in the prevention section of this document.

Personal history of breast cancer

If you have had breast cancer, you also have an increased risk of developing ovarian cancer. There are several reasons for this. Some of the reproductive risk factors for ovarian cancer may also increase breast cancer risk. Also, if you have a strong family history of breast cancer, you may have inherited a mutated BRCA1 or BRCA2 gene (see the section, "Do we know what causes ovarian cancer?"). You have a strong family history if one or more of your close relatives age 50 or younger has or had ovarian cancer.

Talcum powder

It has been suggested that talcum powder applied directly to the genital area or on sanitary napkins may be carcinogenic (cancer-causing) to the ovaries. Some, studies suggest a very slight increase in risk of ovarian cancer in women who used talc on the genital area. In the past, talcum powder was sometimes contaminated with asbestos, a known cancer-causing mineral. This may explain the association with ovarian cancer in some studies. Body and face powder products have been required by law for more than 20 years to be asbestos-free. However, proving the safety of these newer products will require follow-up studies of women who have used them for many years. There is no evidence at present linking cornstarch powders with any female cancers.

Diet

A recent study of women who followed a low-fat diet for at least 4 years showed a lower risk of ovarian cancer. Some studies have shown a reduced rate of ovarian cancer in women who ate a diet high in vegetables, but other studies disagree. The American Cancer Society recommends eating a variety of healthful foods, with an emphasis on plant sources. Eat at least 5 servings of fruits and vegetables every day, as well as several servings of whole grain foods from plant sources such as breads, cereals, grain products, rice, pasta, or beans. Limit the intake of red meat and processed meats. Even though the impact of these dietary recommendations on ovarian cancer risk remains uncertain, following these recommendations can help prevent several other diseases, including some other types of cancer.

Analgesics

In some studies, both aspirin and acetaminophen have been shown to reduce the risk of ovarian cancer. However, the information is not consistent. Women who do not already take these medicines regularly for other health conditions should not start doing so to try to prevent ovarian cancer. More research is needed on this issue.

Smoking and alcohol use

These do not increase the risk for most ovarian cancers, but some studies have found they increase the risk for the mucinous type.