There are opportunities to prevent ovarian cancer, particularly for people who have inherited a genetic mutation related to the disease.
In the context of cancer, “prevention” refers to actions taken that may decrease the likelihood of developing cancer. Preventing ovarian cancer begins with being aware of factors that might increase your risk, and knowing how you can protect yourself.
Everyone who is born with ovaries has some risk of developing ovarian cancer. This disease impacts 1 in 75 Canadian females, and some are at greater risk than others due to age, ethnicity, family history of certain cancers, reproductive history, and the presence of specific genetic mutations.
Risk reduction for ovarian cancer can be broadly categorized as surgical and non-surgical:
A person’s ovarian cancer risk can be reduced by having surgery to remove their ovaries and/or fallopian tubes before they develop ovarian cancer. There are two types of surgeries to reduce ovarian cancer risk:
- Risk-reducing surgery: these surgeries are done for people who are at an increased risk of ovarian cancer due to an inherited genetic mutation. These surgeries are done with the explicit purpose of reducing ovarian cancer risk and involve the removal of both ovaries and fallopian tubes. This surgery is called a risk-reducing salpingo-oophorectomy (RRSO).
- Opportunistic surgery: these surgeries are done for people at average risk of ovarian cancer (anyone born with ovaries). This involves “jumping on the opportunity” of an unrelated surgery. For example, if a person is having pelvic surgery that is unrelated to ovarian cancer (for example, having their “tubes tied”, or having a hysterectomy), they can ask to have their fallopian tubes removed in order to reduce their ovarian cancer risk (the most common type of ovarian cancer starts in the fallopian tubes). This surgery is called an opportunistic salpingectomy.
A person’s ovarian cancer risk can also be reduced by disrupting their ovulation .* Ovulation can be disrupted in different ways, including with the use of birth control pills and with pregnancy/breastfeeding.
*The incessant ovulation hypothesis is a theory that suggests that ovarian cancer may be related to the number of times a person has ovulated throughout their lifetime. The theory proposes that ovulation is an inflammatory event that may increase ovarian cancer risk, and therefore the more times a person ovulates, the greater their risk of ovarian cancer.
For expert advice, talk to your doctor.
Family History
At this time, about 25% of ovarian cancers are known to be hereditary, which means that they “run in the family”. This number may increase as scientists discover more genetic mutations. If you have a family history of ovarian, breast, prostate, pancreatic, endometrial, or colorectal cancer on either side of your family, there is a possibility of a genetic mutation being passed from generation to generation. Some genetic mutations are more common in certain ethnic communities, including people with the following backgrounds: French Canadian, Ashkenazi Jewish, Icelandic, Dutch, and Eastern European.
Genetic Mutations
Genes carry the instructions cells need to grow and function. A genetic mutation occurs when a gene is altered and stops working as it should. Certain genetic mutations, such as BRCA gene mutations, increase a person’s risk of ovarian cancer and other diseases.
There are two categories of genetic mutations: germline (inherited) and somatic:
A genetic mutation that is inherited from a biological parent is called a germline mutation and can be found in all the body’s cells. Germline mutations can be passed down from both the biological mother and biological father, so it is important to review the medical history on both sides of your family. Germline mutations can put you at risk for more than one type of cancer. For example, a BRCA mutation increases your risk for several cancers, including but not limited to ovarian, breast, prostate, and pancreatic cancer.
A genetic mutation that develops during one’s lifetime is called a somatic mutation and is found only in the cells of the tumour. Therefore, somatic mutations are not passed down through families. These types of mutations may be the result of a mistake that happens when a cell is dividing, or from certain environmental exposures (for example, smoking or UV rays).
The two main hereditary syndromes associated with ovarian cancer are Hereditary Breast and Ovarian Cancer Syndrome (HBOC) and Lynch Syndrome.
- HBOC increases a female’s risk of both breast and ovarian cancer. HBOC is connected to germline (inherited) BRCA 1 and BRCA 2 mutations and accounts for most cases of ovarian cancers that run in families. Everyone is born with BRCA 1 and 2 genes. These genes are tumour suppressors, meaning that they prevent the body from developing tumours. If these genes cannot perform their normal function, our bodies are less able to protect us from developing cancer. A BRCA 1 mutation increases a female’s risk of ovarian cancer to 39-50% by age 70. For a BRCA 2 mutation, the risk is 11-18% by age 70. For context, a person at average risk for ovarian cancer is at a 1.4% lifetime risk of developing the disease. HBOC is most commonly associated with high grade serous epithelial ovarian cancer.
- If you have high grade serous ovarian cancer, it is important to talk to your doctor about whether you might have HBOC so you can address your risk of other cancers. Knowing of a BRCA mutation will also help you and your medical team determine your treatment plan, as certain treatments work particularly well for those with a BRCA mutation, and some clinical trials are open to those with particular genetic mutations.
- If you do have HBOC, talk to your biological relatives so that they are aware that they are also at risk. This will give them the opportunity to pursue genetic testing and prevention opportunities.
- Lynch Syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited condition that puts people at increased risk for certain types of cancer at a younger age, including but not limited to ovarian, colorectal, and uterine cancers. Mutations in the following genes are associated with Lynch Syndrome: MLH1, MSH2, MSH6, PMS2, EPCAM. Populations at risk for having Lynch Syndrome have:
- Three or more relatives with a Lynch Syndrome-related cancer, and one relative must be a first-degree relative (such as a parent, sibling, or child) of the other two.
- At least two generations with cancer (such as a parent and child).
- One or more cases of cancer diagnosed younger than age 50.
- Lynch Syndrome accounts for a very small percentage of ovarian cancers and is often associated with endometrioid and clear cell ovarian cancer. If you have one of these types of ovarian cancer, it is important to talk to your doctor about whether you may have Lynch Syndrome so that you can assess your risk for other cancers, including colorectal and uterine cancer.
- If you do have Lynch Syndrome, talk to your biological relatives so that they are aware that they are also at risk. This will give them the opportunity to pursue genetic testing and prevention opportunities.
You may have a genetic mutation that increases your risk of ovarian cancer, even if no one in your biological family has had ovarian cancer or other related cancers. This may be because you have a small family with few female biological relatives, or the mutation may be passed down through your biological father, biological grandfather, and so on. Some of your relatives may also have a genetic mutation, even if they have not developed cancer. To know for sure, be sure to talk to your doctor about getting a genetic test.
To find a genetics clinic near you, visit https://www.cagc-accg.ca/
Genetic testing
The only way to know for sure if you have a genetic mutation is to get a genetic test. A genetic test provides valuable information to people with ovarian cancer, as knowing of a genetic mutation can help them make decisions about which treatment options are best for them. Genetic tests can also help the biological relatives of a person with ovarian cancer learn more about their risk for certain cancers and how to take action to reduce their risk, if appropriate.
Germline genetic testing is done using a blood or saliva sample. This test looks for a mutation that you inherited from a biological parent. The genes that are tested for will vary across provinces and territories.
There are many possible results of a genetic test, and it is important to understand and be prepared for the possibilities.
- Positive result: (this may also be called a pathogenic mutation) this means that a genetic mutation has been identified and this mutation is linked to an increased risk of a specific disease (for example, ovarian cancer).
- Inconclusive result: (this may also be called a variant of unknown significance – VUS) this means that a genetic mutation has been identified, but this mutation has not yet been definitively linked to a specific disease. It is important to note that the classifications of genetic mutations change over time, and many VUS are reclassified as benign, meaning that they do not cause harm. At this time, it is the individual’s responsibility to contact their genetic clinic to find out if their VUS has been reclassified as a pathogenic or benign mutation.
- Benign variant: this means that a genetic mutation was detected, but that it does not cause any problems.
- Negative: this means that no genetic mutations were found.
Most people with ovarian cancer will test negative for a related genetic mutation. This is because most ovarian cancers are not related to an inherited genetic mutation that we know about at this time. Remember, this may change as more people get genetic testing and scientists learn more. For this reason, you are encouraged to contact the clinic that performed your genetic test every few years to request to have your sample retested.
If your doctor tells you that you are not eligible for genetic testing, there are options available to you. For example, there are private companies that do genetic testing. You would have to pay for these tests. There is also a major research project being conducted out of Women’s College Research Institute in Toronto, Ontario called The Screen Project. The Screen Project is enrolling any Canadian over age 18 for BRCA 1 and BRCA 2 genetic testing.
Recommendations based on genetic testing results
If you test positive for a genetic mutation that increases your risk of ovarian cancer, it is very important to talk to your doctor about how to reduce your risk. One way to significantly reduce your risk of ovarian cancer is to have a surgery called a risk-reducing salpingo-oophorectomy (RRSO). During this surgery, both fallopian tubes and ovaries are removed in order to reduce a person’s risk of ovarian cancer.
BRCA1
- Estimated Lifetime Risk of Ovarian Cancer: 39-44% by age 70
- Recommended age for RRSO: 35-40 years
BRCA2
- Estimated Lifetime Risk of Ovarian Cancer: 11-18% by age 70
- Recommended age for RRSO: 40-45 years
BRIP1
- Estimated Lifetime Risk of Ovarian Cancer: Approximately 6% by age 80
- Recommended age for RRSO: Consider at 45-50 years
MLH1
- Estimated Lifetime Risk of Ovarian Cancer: 20% by age 70
- Recommended age for RRSO: Timing individualized for all people with Lynch Syndrome
MSH2
- Estimated Lifetime Risk of Ovarian Cancer: 24% by age 70
- Recommended age for RRSO: Timing individualized for all people with Lynch Syndrome
RAD51C
- Estimated Lifetime Risk of Ovarian Cancer: 11% by age 80
- Recommended age for RRSO: Consider at 45-50 years
RAD51D
- Estimated Lifetime Risk of Ovarian Cancer: 13% by age 80
- Recommended age for RRSO: Consider at 45-50 years
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