Ovarian Cancer Risk Factors

A risk factor is anything that increases your chance of getting a disease like cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.

But having a risk factor, or even many, does not mean that you will get the disease. And some people who get the disease may not have any known risk factors. Researchers have discovered several risk factors that might increase a woman's chance 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.

Factors that increase your risk of ovarian cancers

Getting older

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.

Being overweight or obese

Obesity has been linked to a higher risk of developing many cancers. The current information available for ovarian cancer risk and obesity is not clear. Obese women (those with a body mass index [BMI] of at least 30) probably have a higher risk of developing ovarian cancer, but not necessarily the most aggressive types, such as high-grade serous cancers. Obesity may also negatively affect the overall survival of a woman with ovarian cancer.

Having children later or never having a full-term pregnancy

Women who have their first full-term pregnancy after age 35 or who never carried a pregnancy to term have a higher risk of ovarian cancer.

Taking hormone therapy after menopause

Women using estrogens alone or with progesterone after menopause have an increased risk of developing ovarian cancer compared to women who have never used hormones.

Having a 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 can also come from your father's side.

A family history of some other types of cancer such as colorectal and breast cancer is linked to an increased risk of ovarian cancer. This is because these cancers can be caused by an inherited mutation (change) in certain genes that cause a family cancer syndrome that increases the risk of ovarian cancer.

Having a family cancer syndrome

Up to 25% of ovarian cancers are a part of family cancer syndromes resulting from inherited changes (mutations) in certain genes.

Hereditary breast and ovarian cancer syndrome (HBOC)

This syndrome is caused by inherited mutations in the genes BRCA1 and BRCA2, as well as possibly some other genes that have not yet been found. This syndrome is linked to a high risk of breast cancer as well as ovarian, fallopian tube, and primary peritoneal cancers. The risk of some other cancers, such as pancreatic cancer and prostate cancer, are also increased.

Mutations in BRCA1 and BRCA2 are also responsible for most inherited ovarian cancers. Mutations in BRCA1 and BRCA2 are about 10 times more common in those who are Ashkenazi Jewish than those in the general U.S. population.

The lifetime ovarian cancer risk for women with a BRCA1 mutation is estimated to be between 35% and 70%. This means that if 100 women had a BRCA1 mutation, between 35 and 70 of them would get ovarian cancer. For women with BRCA2 mutations the risk has been estimated to be between 10% and 30% by age 70. These mutations also increase the risks for primary peritoneal carcinoma and fallopian tube carcinoma.

In comparison, the ovarian cancer lifetime risk for the women in the general population is less than 2%.

 

Hereditary nonpolyposis colon cancer (HNPCC)

Women with this syndrome have a very high risk of colon cancer and also have an increased risk of developing cancer of the uterus (endometrial cancer) and ovarian cancer. Many different genes can cause this syndrome. They include MLH1, MSH2, MSH6, PMS2, and EPCAM. The lifetime risk of ovarian cancer in women with hereditary nonpolyposis colon cancer is about 10%. Up to 1% of all ovarian epithelial cancers occur in women with this syndrome. Another name for HNPCC is Lynch syndrome.

Peutz-Jeghers syndrome

People with this rare genetic syndrome develop polyps in the stomach and intestine while they are teenagers. They also have a high risk of cancer, particularly cancers of the digestive tract (esophagus, stomach, small intestine, colon). Women with this syndrome have an increased risk of ovarian cancer, including both epithelial ovarian cancer and a type of stromal tumor called sex cord tumor with annular tubules (SCTAT). This syndrome is caused by mutations in the gene STK11.

MUTYH-associated polyposis

People with this syndrome develop polyps in the colon and small intestine and have a high risk of colon cancer. They are also more likely to develop other cancers, including cancers of the ovary and bladder. This syndrome is caused by mutations in the gene MUTYH.

Other genes associated with hereditary ovarian cancer

Besides the gene mutations mentioned above, there are other genes linked to ovarian cancer. These include ATM, BRIP1, RAD51C, RAD51D, and PALB2. Some of these genes are also associated with cancers such as breast and pancreas.

Using fertility treatment

Fertility treatment with in vitro fertilization (IVF) seems to increase the risk of the type of ovarian tumors known as "borderline" or "low malignant potential" (described in What Is Ovarian Cancer?). Other studies, however, have not shown an increased risk of invasive ovarian cancer with fertility drugs. If you are taking fertility drugs, you should discuss the potential risks with your doctor.

Having had breast cancer

If you have had breast cancer, you might 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 and hereditary breast and ovarian cancer syndrome, which is linked to an increased risk of ovarian cancer.

Smoking

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

Factors with unclear effects on ovarian cancer risk

Androgens

Androgens, such as testosterone, are male hormones. There appears to be a link between certain androgens and specific types of ovarian cancer, but further studies of the role of androgens in ovarian cancer are needed.

Talcum powder

It has been suggested that talcum powder might cause cancer in the ovaries if the powder particles (applied to the genital area or on sanitary napkins, diaphragms, or condoms) were to travel through the vagina, uterus, and fallopian tubes to the ovary.

Many studies in women have looked at the possible link between talcum powder and cancer of the ovary. Findings have been mixed, with some studies reporting a slightly increased risk and some reporting no increase. Many case-control studies have found a small increase in risk. But these types of studies can be biased because they often rely on a person’s memory of talc use many years earlier.  One prospective cohort study, which would not have the same type of potential bias, has not found an increased risk. A second found a modest increase in risk of one type of ovarian cancer.

For any individual woman, if there is an increased risk, the overall increase is likely to very be small. Still, talc is widely used in many products, so it is important to determine if the increased risk is real. Research in this area continues.

Diet

Some studies have shown a reduced rate of ovarian cancer in women who ate a diet high in vegetables or a low fat diet, but other studies disagree. The American Cancer Society recommends following a healthy eating pattern that includes plenty of fruits, vegetables, and whole grains, and that limits or avoids red and processed meats, sugary drinks, and highly processed foods. 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.

Factors that can lower risk of ovarian cancer

Pregnancy and breastfeeding

Women who have been pregnant and carried it to term before age 26 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 risk is lower the longer the pills are used. This lower risk continues for many years after the pill is stopped. Other forms of birth control such as tubal ligation (having fallopian tubes tied) and short use of IUDs (intrauterine devices) have also been associated with a lower risk of ovarian cancer.

A hysterectomy (removing the uterus without removing the ovaries) also seems to reduce the risk of getting ovarian cancer by about one-third.