Your risk depends on your medical and family history of ovarian cancer. For example, having one relative with ovarian cancer means you are more likely than average to get it. But if you have more than one relative with this cancer, your chances of getting it are higher. You may want to talk to a genetic counsellor.

Other family cancers may also affect your risk for ovarian cancer. Ovarian cancer and breast cancer can be related to BRCA gene changes. Women from families who inherit the gene changes for Lynch syndrome (also called hereditary non-polyposis colorectal cancer syndrome, or HNPCC) are also at increased risk for getting ovarian and other cancers.

To understand how a family history of ovarian cancer can affect your chances of getting it, look at the numbers below. Remember that everyone's case is different. These numbers may not show what will happen in your case.

• An average woman has a very low risk. Out of 100 average women, 1 will get ovarian cancer.
• A woman with one family member (mother, sister, daughter) who had this cancer has a slightly higher risk. Out of 100 women with one family member who has had this cancer, 5 will get ovarian cancer.
• A woman with at least two first-degree relatives (meaning mother, sister, or daughter) who had this cancer has a higher risk. Out of 100 women with two relatives who have had it, 7 women will get ovarian cancer.
• Women with the BRCA gene change have the highest risk. Out of 100 women who have the BRCA1 gene change, about 40 will get ovarian cancer. Out of 100 women who have the BRCA2 gene change, about 20 will get ovarian cancer.^{footnote 1}

If you don't know whether you are at high risk, talk to your doctor. A genetic counsellor can also help you. Genetic testing may be an option for some women.

The most important benefit of surgery to remove your ovaries is that your chance of getting ovarian cancer goes way down. This may lower your risk so that it is the same or only slightly higher than the average woman's risk.

• Removing your ovaries makes you start menopause if you haven't started it already. Menopause often has symptoms like hot flashes, vaginal dryness, urinary frequency, and decreased sexual interest. And it raises your risk for other diseases, such as heart disease and osteoporosis.
• When your ovaries are removed, you can no longer get pregnant.
• Removing the ovaries does not always prevent cancer. Sometimes a woman already has cancer before the surgery but doesn't know it because she has no symptoms. And the cancer cells may already have begun to spread outside the ovaries. In that case, removing the ovaries will not remove all of the cancer cells. Cancer can also start on the abdominal lining after the ovaries are removed, but this is rare.

Being at higher risk for ovarian cancer does not mean you will definitely get it. This is why some women choose not to have surgery. If you decide not to have surgery, you have two other options:

• Birth control pills. Studies show that taking birth control pills lowers the risk of getting ovarian cancer.^{footnote 2}
• Extra checkups and testing. The goal is to find any cancer as early as possible, when the chances of treating it successfully are higher.

There is no proof that having extra screening tests helps women live longer by finding ovarian cancer early. Still, some experts recommend that women with an inherited risk of ovarian cancer have these tests at least once a year, starting at age 35:^{footnote 3}

• Transvaginal ultrasound. Ultrasound uses sound waves to make pictures of body parts. A small hand-held device is passed back and forth over the area in question. In a transvaginal ultrasound, the device fits into a woman's vagina. The test is used to look for tumours in and around the ovaries.
• CA-125 blood test. CA-125 is a protein in your blood. Having more of it than normal can mean you have cancer. The test is usually used to check how well treatment for ovarian cancer is working or to see if the cancer has returned.

For women who have an average risk for ovarian cancer, experts do not recommend using the CA-125 test as a screening test for ovarian cancer. This is because this test often has false-positive results that can lead to unneeded surgery. But some doctors may recommend the CA-125 test and a transvaginal ultrasound for women who have a very high risk of ovarian cancer, such as those with BRCA gene changes. For these women, the benefits of screening may outweigh the harms.

Your doctor might recommend this surgery if genetic testing shows that you have inherited a gene change, such as BRCA or the one for Lynch syndrome (HNPCC), and you are done having children.

If you have not yet gone through menopause, talk with your doctor about starting hormone therapy after your surgery. Hormone therapy may help you avoid the symptoms and risks of early menopause without raising your risk for breast cancer.^{footnote 4}