Risk for ovarian cancer

Some things can affect your risk, or chance, of developing cancer. Certain behaviours, substances or conditions can increase or decrease the risk. Most cancers are the result of many risks. But sometimes cancer develops in people who don't have any risks.

Epithelial ovarian cancer is the most common type of ovarian cancer. The number of new cases of this cancer (called the incidence) increases with age. Most epithelial ovarian cancers are found in women who have gone through menopause. We need more research and can’t say at this time what the risk is for transgender, non-binary and gender-diverse people.

The risks for other types of ovarian cancer are not well known and may not be the same as for epithelial ovarian cancer. But fallopian tube and primary peritoneal cancer share many of the same risks as epithelial ovarian cancer. This is because these cancers start in the same type of tissue.

If you have a genetic condition that increases your risk for one of these cancers, you may need to visit your doctor more often. Talk to your doctor about your risk and if you need to have certain tests to check for epithelial ovarian, fallopian tube or primary peritoneal cancer.

There are several things that could increase or decrease your risk for epithelial ovarian, fallopian tube or primary peritoneal cancer. Some of these risks can't be changed. But in some cases, there are things you can do to lower your risk.

The following can increase your risk for epithelial ovarian, fallopian tube and primary peritoneal cancer:

• family history of epithelial ovarian, fallopian tube or primary peritoneal cancer
• genetic conditions, including BRCA gene mutations, Lynch syndrome and Peutz-Jeghers syndrome
• family history of certain cancers
• personal history of breast cancer
• hormone replacement therapy
• smoking tobacco
• asbestos
• tall adult height
• excess weight
• endometriosis

The following can decrease your risk for epithelial ovarian, fallopian tube and primary peritoneal cancer:

• pregnancy and giving birth
• gynecological surgery
• birth control pills

A family history of epithelial ovarian, fallopian tube or primary peritoneal cancer means that 1 or more close blood relatives have or had one of these cancers. Some families have more cases of any of these cancers than would be expected by chance. Sometimes it's not clear if the family’s pattern of cancer is due to chance, shared lifestyle factors, genes passed from parents to children or a combination of these.

The risk of developing epithelial ovarian, fallopian tube or primary peritoneal cancer is higher if you have 1 or more first-degree relative (mother, sister or daughter) who has (or has had) the disease. The risk is greater if your mother had 1 of these cancers than if your daughter had it. Your risk can be even higher if your relative was diagnosed with the cancer before they were 50 years of age or before they went into menopause.

You can have a slightly higher risk if 1 first-degree relative and 1 second-degree relative (aunt, grandmother or niece) have (or have had) the cancer.

A genetic condition is a disease caused by a change (mutation) in 1 or more genes. Having certain genetic conditions increases the risk of developing certain types of cancer. The following genetic conditions can be inherited and increase the risk of developing epithelial ovarian, fallopian tube or primary peritoneal cancer.

Breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2) normally help control the growth of cancer cells. Changes in these genes increase the risk for epithelial ovarian, fallopian tube and primary peritoneal cancer. BRCA1 and BRCA2 mutations also increase the risks for other types of cancer including breast, pancreatic and prostate cancer. 

Lynch syndrome causes a large number of polyps to develop in the lining of the colon and rectum, but not as many polyps as are found in familial adenomatous polyposis (FAP). Lynch syndrome is also called hereditary non-polyposis colorectal cancer (HNPCC).

There are 2 types of Lynch syndrome:

• type A increases the risk for colorectal cancer
• type B increases the risk of several cancers, including epithelial ovarian and uterine cancer, and colorectal cancer and other digestive system cancers

Peutz-Jeghers syndrome causes dark spots on the mouth and fingers and polyps in the large and small intestines.

Peutz-Jeghers syndrome increases the risk of some ovarian cancers and non-cancerous tumours, including epithelial ovarian cancer and benign stromal tumours. It also increases the risk of developing colorectal, small intestine, stomach, pancreatic and breast cancers.

A family history of breast, colorectal, uterine or pancreatic cancer increases the risk of developing epithelial ovarian cancer.

Women who have been diagnosed with breast cancer have a higher risk of developing epithelial ovarian cancer. This could be because of a BRCA gene mutation. Some of the same risks for breast cancer that are related to menstruation history may also increase the risk of developing epithelial ovarian cancer. These risks include starting your period early (younger than 11 years of age) or starting menopause later (after age 55).

Having been pregnant and giving birth lowers the risk of developing epithelial ovarian cancer. Researchers think that the lower risk may be because the hormones that are present during pregnancy protect against developing epithelial ovarian cancer. The more times you've been pregnant and given birth, the greater the protective effect.

Women who have never been pregnant and given birth have a higher risk of developing epithelial ovarian cancer. It is possible that the higher risk in women who have never been pregnant is linked to the factors that may make it difficult for her to become pregnant.

The risk for epithelial ovarian cancer is also higher in women who have never given birth, even if they have been pregnant. Researchers are not sure if this greater risk is related to the same factors that increase the risk for epithelial ovarian cancer in women who have never been pregnant.

Pregnancy does not appear to have a protective effect for women who have a strong family history of epithelial ovarian cancer or a BRCA gene mutation.

A tubal ligation is surgery that cuts or blocks the fallopian tubes. A salpingectomy is surgery to remove 1 or both of the fallopian tubes. Having either of these surgeries lowers the lifetime risk of developing epithelial ovarian, fallopian tube and primary peritoneal cancer.

A hysterectomy is surgery to remove the uterus. It may also lower the risk of developing epithelial ovarian cancer, but not as much as tubal ligation. Hysterectomy seems to lower the risk when the fallopian tubes and ovaries are also removed (called bilateral salpingo-oophorectomy).

If you have BRCA1 or BRCA2 mutations, you may be offered a bilateral sapling-oophorectomy to reduce your risk of developing epithelial ovarian, fallopian tube and primary peritoneal cancer.

Hormone replacement therapy (HRT) uses female sex hormones (estrogen, progesterone or both) to manage the symptoms of menopause, such as hot flashes, vaginal dryness and mood swings. Using HRT with estrogen alone or combined with progesterone increases the risk for epithelial ovarian cancer. The longer you take estrogen, the greater your risk for epithelial ovarian cancer. Women who have taken HRT for more than 5 years have a greater risk than women who have taken it for less than 5 years. Current users of HRT have a higher risk compared to women who have stopped taking HRT, no matter how long they took it.

Talk to your doctor about the benefits and risks of taking HRT.

Birth control pills (oral contraceptives) are designed to prevent pregnancy. They contain the hormones estrogen and progesterone. Birth control pills lower your risk for epithelial ovarian cancer. 

Learn more about the benefits and risks of hormonal birth control.

Smoking tobacco increases your risk for mucinous carcinoma. This is a type of epithelial ovarian cancer.

All forms of tobacco, including those in commercial tobacco products and e-cigarettes, increase your risk. The more you smoke and the longer you smoke, the greater your risk. The risk of developing mucinous carcinoma decreases with time after you quit smoking.

Learn more about how to live smoke-free.

Asbestos is a group of minerals that occur naturally. Asbestos has been widely used in building materials and many industries. Asbestos increases the risk forfor epithelial ovarian cancer.

Learn more about asbestos and cancer and how to be safe at work.

Tall women have a slightly higher risk for epithelial ovarian cancer. Researchers think this increased risk may be due to developmental factors such as growth and puberty hormones.

Overweight and obesity increase the risk for epithelial ovarian cancer. 

Learn more about how to have a healthy body weight.

The endometrium is the lining of the uterus. Endometriosis is a non-cancerous condition that occurs when the endometrium grows outside of the uterus. It can grow on or around the ovaries, behind the uterus, on the small or large intestine or on the bladder. Women with endometriosis have a higher risk of developing ovarian cancer, especially if there is endometriosis on the ovaries. The risk for certain types of epithelial ovarian cancer, including clear cell carcinoma and endometrioid carcinoma, is higher in women with endometriosis.

The following have been linked with epithelial ovarian cancer, but more research is needed to know for sure that they are risks:

• number of menstrual periods during your lifetime including the number of ovulations, having a first period (called menarche) before the age of 12 years or stopping periods after the age of 55 (late menopause)
• talcum powder
• not eating enough vegetables
• pelvic inflammatory disease
• polycystic ovary syndrome (PCOS)
• sedentary behaviour or sitting for long periods time
• high levels of androgens

The following have been linked with a decreased risk of ovarian cancer, but more research is needed to know for sure that they lower the risk:

• breastfeeding
• aspirin

Significant research shows that there is no link between alcohol or coffee and a higher risk for epithelial ovarian cancer.

To make the decisions that are right for you, ask your doctor questions about risks. Learn how cancer can be prevented and what you can do to reduce your risk.