Does Someone Who Inherits A Cancer Susceptibility Variant Always Get Cancer
No. Even if a cancer susceptibility variant is present in a family, it does not necessarily mean that everyone who inherits the variant will develop cancer. Several factors influence whether a given person with the variant will actually develop cancer. One is the penetrance of the variant. When not all people who carry a variant go on to develop the disease associated with that variant, it is said to have incomplete or reduced penetrance. Hereditary cancer syndromes can also vary in their expressivitythat is, people who inherit the variant may vary in the extent to which they show signs and symptoms of the syndrome, including the development of associated cancers. Lifestyle factors and environmental risks can also influence disease expression.
Should I Be Tested For Genetic Mutations
At-risk families can take blood tests to look for mutations in these genes.
You may want to discuss genetic testing with your doctor if:
- You have two or more blood relatives — mother, sister, aunt, cousin, or daughter — with premenopausal breast cancer or ovarian cancer diagnosed at any age.
- You were diagnosed with breast cancer, especially before menopause, and have a blood relative with breast or ovarian cancer.
- You were diagnosed with ovarian cancer and you have blood relatives who have had ovarian or breast cancer.
- A male in your family has or had breast cancer.
- You or a family member has been diagnosed with bilateral breast cancer .
- You were diagnosed with triple-negative breast cancer before the age of 60.
- You are related to someone who has a BRCA1 or BRCA2 mutation.
- You are of Ashkenazi Jewish descent and have had breast or ovarian cancer or have blood relatives who have had breast or ovarian cancer.
Genetic Testing For Breast Cancer
If you are experiencing a medical emergency, please call 911 or seek care at an emergency room.
The last several years have produced significant advances in the field of genetic testing. Doctors are utilizing preventative measures to decrease cancer risk, and are now using genetic testing to help patients and their families understand their cancer risks. So how does genetic testing work and what are the potential positive outcomes for those with a breast cancer diagnosis? What are the concerns about the risk?
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Criteria For Brca Testing
The current USPSTF guidelines state that the target population for BRCA testing includes high risk individuals who have a personal or family history of breast or ovarian cancers at a young age , that suggests inherited cancer susceptibility, when an individual has access to a health professional who is trained to provide genetic counseling and interpret test results, and when test results will aid in decision making. Recommendations vary, but the following criteria are generally considered when evaluating patients for genetic testing: 1) breast, colorectal, or endometrial cancer diagnosed before age 50, 2) bilateral breast cancer, 3) two primary breast cancers or clustering of breast and ovarian cancer, 4) multiple cancers at a young age, 5) rare cancer presentation at any age, 6) two or more primary types of BRCA1- or BRCA2-related cancers in a single family member, or 7) family history of male breast cancer.
An Er Positive Carcinoma
Testing for expression of the estrogen receptor on in situ and invasive ductal carcinoma is done by immunohistochemistry, using an immunostain for ER in the pathology laboratory. The immunostain binds to the ER protein in the cancer nucleus and is detected by a positive brown color. This in situ and invasive ductal carcinoma is diffusely positive for ER, with 100%, strong labeling of the carcinoma nuclei. Testing for the expression of progesterone receptor is done in the same way.
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Different Kinds Of Findings In Genetic Testing
As the terminology used for different kinds of findings in genetic testing has been widely discussed we shall, in the following, specify how different terms are used in this paper. Let us begin with SF, secondary findings. We take a finding to qualify as a SF when it goes beyond the initial purpose of the genetic test, in the present case the link between pathogenic variants and an increased risk for BC. However, SF should be distinguished from the notion of pleiotropy which is not a secondary finding in the pure sense of the word. To exemplify an instance of pleiotropy, consider a pathogenic variant found in TP53 which increases the risk of developing BC. However, this type of variant also increases the risk of developing other cancer forms such as ovarian cancer and soft tissue sarcoma, among others .
Does the increased risk of developing the other cancer forms qualify as a SF or as an instance of pleiotropy? According to the nomenclature employed in this paper this is determined by how the purpose of the test was described in the first place. Although it may seem strange to describe the increased risk for ovarian cancer indicated by a pathogenic variant in TP53 as a SF from a clinical perspective this is not the case from the index-persons perspective. Accordingly, an underlying assumption for this discussion is that the crucial ethical questions arise in relation to the index-person.
Emotional Risks For Family Members
Genetic testing may also have an emotional impact on family members.
Your genetic counselor may suggest you talk to your family about BRCA1/2 or expanded panel testing before you get tested or before you learn your results. That way you can find out if they want to know about your results.
For people with a BRCA1/2 or other high-risk inherited gene mutation, figuring out how to tell relatives can be hard.
Some family members may value the option of BRCA1/2 or panel testing. Others may be upset, anxious or angry about hearing the news.
If you have concerns about the best way to share the news with your family members, talk with a genetic counselor. You may prefer to write a letter to your relatives , especially if you have a big family. Your genetic counselor may be able to help you write this letter.
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Reasons For Genetic Testing
- To learn whether you have a genetic condition that runs in your family before you have symptoms
- To learn about the chance a current or future pregnancy will have a genetic condition
- To diagnose a genetic condition if you or your child has symptoms
- To understand and guide your cancer prevention or treatment plan
After learning more about genetic testing, you might decide its not right for you. Some reasons might be that its not relevant to you or wont change your medical care, its too expensive, and the results may make you worried or anxious.
The Ethical Relevance Of The Different Ways In Which People Are Approached
The distinction between testing and screening has an ethical importance from the point of view of autonomy. In ordinary health care, the individual seeks health care to have a problem remedied. This is at the initiative of the person herself. All follow up testing and treatment are supposed to be decided upon in a dialogue with the patient according to that patients needs and desires . In population screening, contrarily, there is a standard testing offered to all within the screening program. Besides the challenge of tailored screening to the individual patients needs and desires, this carries with it some pressure to accept the offer to start with: why would testing be offered unless there is a reason to accept it ?
In cascade screening, the situation is analogous to population screening in the sense that relatives have not themselves approached health care to find out their risk of BC. This is, then, a disadvantage in terms of autonomy compared to the ordinary situation where the individual takes the initiative to seek out health care. Moreover, there are some downsides with cascade screening from the point of view of autonomy as such screening differs from population screening as the risk, quite naturally, is higher. This is the defining characteristic of the targeted population, because of their increased risk based upon the fact that one of their relatives had tested positive for a pathogenic variant.
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What Are Brca1 And Brca2
BRCA1 and BRCA2 are genes that produce proteins that help repair damaged DNA. Everyone has two copies of each of these genesone copy inherited from each parent. BRCA1 and BRCA2 are sometimes called tumor suppressor genes because when they have certain changes, called harmful variants , cancer can develop.
People who inherit harmful variants in one of these genes have increased risks of several cancersmost notably breast and ovarian cancer, but also several additional types of cancer. People who have inherited a harmful variant in BRCA1 and BRCA2 also tend to develop cancer at younger ages than people who do not have such a variant.
A harmful variant in BRCA1 or BRCA2 can be inherited from either parent. Each child of a parent who carries any mutation in one of these genes has a 50% chance of inheriting the mutation. Inherited mutationsalso called germline mutations or variantsare present from birth in all cells in the body.
Even if someone has inherited a harmful variant in BRCA1 or BRCA2 from one parent, they would have inherited a normal copy of that gene from the other parent . But the normal copy can be lost or change in some cells in the body during that persons lifetime. Such a change is called a somatic alteration. Cells that dont have any functioning BRCA1 or BRCA2 proteins can grow out of control and become cancer.
Types Of Genetic Test Results
- Positive the test found a genetic change known to cause disease.
- Negative the test did not find a genetic change known to cause disease. Sometimes a negative result occurs when the wrong test was ordered or there isnt a genetic cause for that persons symptoms. A true negative is when there is a known genetic change in the family and the person tested did not inherit it. If your test results are negative and there is no known genetic change in your family, a negative test result may not give you a definite answer. This is because you might not have been tested for the genetic change that runs in your family.
- Uncertain a variant of unknown or uncertain significance means there isnt enough information about that genetic change to determine whether it is benign or pathogenic .
A good way to think about genetic testing is as if youre asking the DNA a question. Sometimes we dont find an answer because we werent asking the right question or science just didnt have the answer yet.
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Hereditary Breast And Ovarian Cancer Syndrome
Women who have a BRCA1 mutation have a 15 to 60% lifetime risk for ovarian cancer and women with BRCA2 mutations have an estimated 10 to 27% cumulative risk.7,8,9,10,22. Chan and Parmigiani’s meta-analysis found a 40% and 18% cumulative risk for ovarian cancer by age 70 years in BRCA1 and BRCA2 carriers, respectively. In addition, women with BRCA2 mutations tend to develop ovarian cancer at an older age compared to those with BRCA1 mutations.10,22
There have been several studies that have looked at the pathological features of ovarian tumors from BRCA1 and BRCA2 carriers. Most of these studies have found that BRCA1– and BRCA2-associated ovarian cancers are primarily high-grade, advanced stage, serous tumors.33,34,35,36 Endometrioid histology is the next most common ovarian tumor pathology associated with BRCA-positive status.37 Mucinous ovarian tumors occur at a much lower frequency in BRCA carriers when compared to noncarriers.36,37 Borderline ovarian tumors have also been identified in BRCA carriers, although they also occur at a frequency lower than control populations.37,38
Inherited Gene Mutations That Increase Breast Cancer Risk
Most women who get breast cancer dont have an inherited gene mutation.
In the U.S., 5-10 percent of breast cancers are linked to an inherited gene mutation . About half of these breast cancers are linked to a BRCA1 or BRCA2 gene mutation .
The lifetime risk of breast cancer is increased 20-49 percent for women with moderate-risk inherited gene mutations and 50 percent or more for women with high-risk inherited gene mutations.
Inherited mutations in any of these genes can increase the risk of breast cancer:
- ATM
- TP53
Most of these gene mutations also increase the risk of other cancers.
BRCA1/2 gene mutations are the most well-known of these high-risk gene mutations. The others are less common and theres still much to learn about them. Most dont increase the risk of breast cancer as much as BRCA1/2 gene mutations do.
Some inherited gene mutations have only recently been shown to increase the risk of breast cancer. Data on these mutations and their related cancer risks are still emerging and will likely change over time.
Learn more about inherited gene mutations and breast cancer risk.
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What Is Involved In Genetic Testing For Breast Cancer And What Do The Results Mean
Dr. Hartmann answers the question: ‘What Goes Into Genetic Cancer Testing?’
& #151 — Question: What is involved in genetic testing for breast cancer and what do the results mean?
Answer: The question often comes up: should I be tested for the breast cancer gene? And actually we know two genes right now — BRCA1, BRCA2, that stand for “Breast Cancer 1” “Breast Cancer 2” — that are behind this susceptibility in the dramatically affected families where about half of the women in the family are developing breast cancer at an early age and ovarian cancer can be seen as well.
So if we have a patient who gives us that kind of family history — also an Ashkenazi Jewish background – those women have a higher likelihood of inheriting such a mutation, then we certainly consider genetic testing. Why? It will help us counsel this individual woman. Is she at risk for ovarian cancer? Is she at a higher risk for a second breast cancer? And relatives of hers can be tested for the mutation if one is found, even though they haven’t had cancer yet. They can then be counseled, what is their risk of developing breast cancer and ovarian cancer? So that’s the population where we often recommend genetic testing.
If The Result Is Variance Of Unknown Or Uncertain Significance
When genetic tests show that a person has an unusual form of a gene, but doctors dont know what this gene change means the result is called a variance of unknown or uncertain significance . It may be a normal variant, simply a different version of gene that isnt seen often enough to be sure, or there may be some other explanation.
For some, a VUS result can cause anxiety, frustration, and even anger because this result gives no information to guide future decisions. Your health care provider or genetic counselor can help you understand what the results might mean for you and your family and help you cope with them.
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How Much Does An Inherited Harmful Variant In Brca1 Or Brca2 Increase A Womans Risk Of Breast And Ovarian Cancer
A womans lifetime risk of developing breast and/or ovarian cancer is markedly increased if she inherits a harmful variant in BRCA1 or BRCA2, but the degree of increase varies depending on the mutation.
Breast cancer: About 13% of women in the general population will develop breast cancer sometime during their lives . By contrast, 55%72% of women who inherit a harmful BRCA1 variant and 45%69% of women who inherit a harmful BRCA2 variant will develop breast cancer by 7080 years of age . The risk for any one woman depends on a number of factors, some of which have not been fully characterized.
Like women with breast cancer in general, those with harmful BRCA1 or BRCA2 variants also have an increased risk of developing cancer in the opposite breast in the years following a breast cancer diagnosis . The risk of contralateral breast cancer increases with the time since a first breast cancer, reaching 20%30% at 10 years of follow-up and 40%50% at 20 years, depending on the gene involved.
Ovarian cancer: About 1.2% of women in the general population will develop ovarian cancer sometime during their lives . By contrast, 39%44% of women who inherit a harmful BRCA1 variant and 11%17% of women who inherit a harmful BRCA2 variant will develop ovarian cancer by 7080 years of age .
The Relevance Of How Genetic Testing Is Organized
Ways in which individuals may take a genetic test
There are at least four ways in which an individual may encounter a genetic test for BC. These encounters may take the form of screening or testing. Following Juth & Munthe we shall understand the difference between the two by appealing to by whom the test is initiated. There are two forms of screening which are initiated by someone other than the index-person, namely population screening and cascade screening. Population screening is a screening program which usually targets people of certain age range within a countrys or regions population. Cascade screening is a more targeted form of screening, where individuals with a recognizably higher genetic risk for a specific disease are offered to take a test, for example, when a test is being offered to other at-risk relatives where a pathogenic variant has been identified in the index-person. Cascade screening is therefore different from population screening but shares the feature that the initiative to testing comes from someone other than the index-person. Accordingly, we shall take a defining characteristic of the notion of screening to be that testing is initiated by the health care sector rather than the individual herself.
The following discussion has relevance for these four kinds of testing. This paper focuses on predictive testing of adults and consequently leaves other types of genetic testing aside in the following.
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