Ovarian Cancer

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Causes, Risk Factors, and Prevention TOPICS

What are the risk factors for ovarian cancer?

A risk factor is anything that changes your chance of getting a disease like cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for a number of cancers.

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 don’t apply to other less common types of ovarian cancer like 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 63 years of age or older.

Obesity

Various studies have looked at the relationship of obesity and ovarian cancer. Overall, it seems that obese women (those with a body mass index of at least 30) have a higher risk of developing ovarian cancer.

Reproductive history

Women who have been pregnant and carried it to term have a lower risk of ovarian cancer than women who have not. The risk goes down with each full-term pregnancy. Breastfeeding may lower the risk even further.

Birth control

Women who have used oral contraceptives (also known as birth control pills or the pill) have a lower risk of ovarian cancer. The lower risk is seen after only 3 to 6 months of using the pill, and the risk is lower the longer the pills are used. This lower risk continues for many years after the pill is stopped.

A recent study found that the women who used depot medroxyprogesterone acetate (DMPA or Depo-Provera CI®), an injectable hormonal contraceptive had a lower risk of ovarian cancer. The risk was even lower if the women had used it for 3 or more years.

Gynecologic surgery

Tubal ligation (having your tubes tied) may reduce the chance of developing ovarian cancer by up to two-thirds. A hysterectomy (removing 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 (Clomid®) 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" (described in the section, "What is ovarian cancer?"). 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 (compared to fertile women) even if they don’t use fertility drugs. This might be in part because they haven't given birth or used birth control pills (which are protective). More research to clarify these relationships is now underway.

Androgens

Androgens are male hormones. Danazol, a drug that increases androgen levels, was linked to an increased risk of ovarian cancer in a small study. In a larger study, this link was not confirmed, but women who took androgens were found to have a higher risk of ovarian cancer. Further studies of the role of androgens in ovarian cancer are planned.

Estrogen therapy and hormone 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 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.

Up to 10% of ovarian cancers result from an inherited tendency to develop the disease. A family history of some other types of cancer caused by an inherited mutation (change) in certain genes can increase the risk of ovarian cancer. For example, mutations in the genes BRCA1 and BRCA2 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 outcome than patients who don’t 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. See the “Additional resources for ovarian cancer” section for more information on these topics.

Personal history of breast cancer

If you have had breast cancer, you may 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 affect breast cancer risk. The risk of ovarian cancer after breast cancer is highest in those women with a family history of breast cancer. A strong family history of breast cancer may be caused by an inherited mutation in the BRCA1 or BRCA2 genes. These mutations can also cause ovarian cancer. (See the section, "Do we know what causes 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 might 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 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 2 ½ cups 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 amount of red meat and processed meats you eat. Even though the effect of these dietary recommendations on ovarian cancer risk remains uncertain, following them 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 isn’t consistent. Women who don’t 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

Smoking doesn’t increase the risk of ovarian cancer overall, but it is linked to an increased risk for the mucinous type.

Drinking alcohol is not linked to ovarian cancer risk.


Last Medical Review: 03/21/2013
Last Revised: 02/06/2014