Are Harmful Variants In Brca1 And Brca2 More Common In Certain Racial/ethnic Populations Than Others
Yes. The likelihood of carrying an inherited mutation in BRCA1 or BRCA2 varies across specific population groups. While the prevalence in the general population is about 0.2%0.3% , about 2.0% of people of Ashkenazi Jewish descent carry a harmful variant in one of these two genes and the variants are usually one of three specific variants, called founder mutations. Other populations, such as Norwegian, Dutch, and Icelandic peoples, also have founder mutations .
Different racial/ethnic and geographic populations also tend to carry different variants in these genes. For instance, African Americans have BRCA1 variants that are not seen in other racial/ethnic groups in the United States . Most people of Ashkenazi Jewish descent in the United States who carry a BRCA variant have one of three specific variants . In the Icelandic population, a different variant in BRCA1 is common among those who inherit a mutation in BRCA1.
Understanding Breast Cancer Genetic Testing
There are two known breast cancer genes : BRCA1 and BRCA2. When a BRCA gene is mutated, this can significantly increase the risk of developing breast cancer and ovarian cancer.
Icon Medical Oncologist Dr Shang Yeap Heng Oon was recently invited to answer questions from LHZB readers on genetic testing for breast cancer, which featured on 26 October 2021.
Read the article below to find out more!
My mother had breast cancer before and is now in remission. Should I undergo genetic testing? Why didnt the doctor recommend for me to receive genetic testing?
Most breast cancer patients and their family members do not need to receive genetic testing. This is because genetic testing only detects the genetic causes of breast cancer. Hereditary breast cancers typically account for up to 10% of all breast cancers, so genetic testing wont be appropriate for most breast cancers.
Who should receive genetic testing for breast cancer? Generally speaking, breast cancer patients are the first to be considered. Therefore, if genetic testing is necessary, the doctor will consider your mother to first receive genetic testing. Factors that determine the need for genetic testing include the age of the person when diagnosed with breast cancer, type of breast cancer, number of family members with breast cancer and any family history of other types of cancer, such as ovarian cancer.
If I test positively for an inherited breast cancer gene mutation, does this mean I will definitely get breast cancer?
What Other Cancers Are Linked To Harmful Variants In Brca1 And Brca2
Harmful variants in BRCA1 and BRCA2 increase the risk of several additional cancers. In women, these include fallopian tube cancer and primary peritoneal cancer , both of which start in the same cells as the most common type of ovarian cancer. Men with BRCA2 variants, and to a lesser extent BRCA1 variants, are also at increased risk of breast cancer and prostate cancer . Both men and women with harmful BRCA1 or BRCA2 variants are at increased risk of pancreatic cancer, although the risk increase is low .
In addition, certain variants in BRCA1 and BRCA2 can cause subtypes of Fanconi anemia, a rare syndrome that is associated with childhood solid tumors and development of acute myeloid leukemia . The mutations that cause these Fanconi anemia subtypes have a milder effect on protein function than the mutations that cause breast and ovarian cancer. Children who inherit one of these variants from each parent will develop Fanconi anemia.
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The National Hereditary Breast Cancer Helpline Has Celebrated Its 25th Anniversary In Style This Year With The Return Of Its Annual Ball At Chesterfields Technique Stadium
Prominent members of the charity and special guests gathered at the home of the Spireites on Sunday, November 13, to mark the momentous occasion with a three-course meal, drinks reception and music.
It is the first time the annual ball has been held for two years due to the Covid-19 pandemic with this years event also acting as a premiere for a new charity single set to be released next month.
The charitys founder, Wendy Watson, was just 37 when she became Britain’s first woman to have both breasts removed in 1992 in a desperate bid to halt the disease which had devastated three generations of her family.
She started The National Hereditary Breast Cancer Helpline just four years later and has fielded thousands of calls and emails from all groups of people with concerns of their familial increased risk since its inception.
As well as this, Wendy has been a speaker at many conferences including Breakthrough, Breast Cancer Care, Royal College of Nursing and sat on committees of several trials, including the MARIBS study into MRIs, and the European series of Psychological Impact of Genetic Testing for Breast Cancer.
In 2018 on the 70th anniversary of the NHS, she was also credited with changing the way breast cancer is treated.
Wendy, who was awarded an MBE in 2012 for her work, was just one of the guests at the annual National Hereditary Breast Cancer Helpline ball.
Heres a selection of pictures from the nights celebrations:
Some Facts About Breast Cancer
- Breast cancer is one of the most common cancers in the world.
- In the UK about 1 in 8 women develop breast cancer at some stage of their lives.
- The biggest risk factor for developing breast cancer is increasing age. Most cases develop in women over the age of 50.
- Of women who do develop breast cancer, most do not have a strong family history of the disease. However, some women do come from families where breast cancer occurs more often than usual .
- If breast cancer is detected in an early stage, there is a good chance of a cure. X-ray testing of the breast can detect breast cancer at an early stage.
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Brca1 And Brca2 Genetic Mutations
Most inherited cases of breast cancer are associated with mutations in two genes: BRCA1 and BRCA2 .
Everyone has BRCA1 and BRCA2 genes. The function of the BRCA genes is to repair cell damage and keep breast, ovarian, and other cells growing normally. But when these genes contain mutations that are passed from generation to generation, the genes don’t function normally and breast, ovarian, and other cancer risk increases. BRCA1 and BRCA2 mutations may account for up to 10% of all breast cancers, or 1 out of every 10 cases.
Having a BRCA1 or BRCA2 mutation doesn’t mean you will be diagnosed with breast cancer. Researchers are learning that other mutations in pieces of chromosomes called SNPs may be linked to higher breast cancer risk in women with a BRCA1 mutation as well as women who didn’t inherit a breast cancer gene mutation.
Women who are diagnosed with breast cancer and have a BRCA1 or BRCA2 mutation often have a family history of breast cancer, ovarian cancer, and other cancers. Still, most people who develop breast cancer did not inherit a genetic mutation linked to breast cancer and have no family history of the disease.
You are substantially more likely to have a genetic mutation linked to breast cancer if:
If one family member has a genetic mutation linked to breast cancer, it does not mean that all family members will have it.
What Is Familial Breast Cancer
Family history is a very important part of breast cancer risk. About 5-10% of breast cancer cases are hereditary. Hereditary cancer happens when changes or mutations in genes are passed down from your parents. However, just because there seems to be a family history of cancer does not mean you will get cancer. Testing for genetic mutations is one way to get an idea of your risk of developing cancer.
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How Is Hboc Inherited
Normally, each person has 2 copies of each gene in their bodys cells: 1 copy is inherited from a persons mother and 1 copy is inherited from a persons father. HBOC follows an autosomal dominant inheritance pattern. This means that a mutation needs to happen in only 1 copy of the gene for the person to have an increased risk of getting that disease. This means that a parent with a gene mutation may pass along a copy of their normal gene or a copy of the gene with the mutation. Therefore, a child who has a parent with a mutation has a 50% chance of inheriting that mutation. A sibling or parent of a person who has a mutation also has a 50% chance of having inherited the same mutation. However, if the parents test negative for the mutation , the risk to the siblings significantly decreases but their risk may still be higher than an average risk.
What Other Gene Mutations Are Important In Hereditary Breast Cancer
In addition to the often talked about BRCA gene mutations, there are a significant number of other inherited gene mutations that increase the risk of developing breast cancer. In fact, it’s thought that mutations in over 100 genes contribute to risk, and the number of non-BRCA gene mutations that raise breast cancer risk is expected to grow as our knowledge of the genetics of cancer increases.
In addition to BRCA1 and BRCA2 gene mutations, some of these include mutations in ATM, PALB2, PTEN, CDH1, CHEK2, TP53, STK11, PMS2, and more. Let’s look at how important these non-BRCA1/BRCA2 mutations are in familial breast cancer, and some of the characteristics of those more commonly found.
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Breast Cancer And Genetic Testing
At the current time, testing is available for BRCA gene mutations, as well as mutations ATM, CDH1, CHEK2, MRE11A, MSH6, NBN, PALB2, PMS2, PTEN, RAD50, RAD51C, SEC23B, and TP53, with this area expected to expand dramatically in the near future.
Having these tests available, however, raises many questions. For example, who might have hereditary breast cancer and who should be tested? What should you do if you test positive for one of these genes?
Ideally, any testing should be done only with the guidance and help of a genetic counselor. There are two reasons for this.
One is that it can be devastating to learn that you carry a mutation that may increase your risk, and the guidance of someone who is aware of recommended management and screening is invaluable.
As noted earlier, some mutations confer a high risk and others a much lower risk. Some mutations might be of more concern earlier in life , whereas others might not require early screening. A genetic counselor can help you learn about what is currently recommended with regard to screening for your particular mutation while taking into account any other risk factors you might have.
The other reason genetic counseling is so important is that you may have a significant risk of developing breast cancer even if your tests are negative. There is much yet to learn, and a genetic counselor can help you look at your family history to see if you may carry a high risk despite negative testing, and plan screening accordingly.
What Can You Do Managing Your Breast Cancer Risk
- Being breast aware. Women of all ages are encouraged to be aware of how their breasts normally look and feel. If you notice any new or unusual changes, please contact your doctor without delay.
- Participating in breast cancer screening. Free routine mammographic screening is available in each state for women aged 50-74 through BreastScreen Australia. Women aged 40-49, or over 75, are also entitled to a free mammogram, however, they receive no reminder prompts, like women aged 50-74 do. Book online or contact BreastScreen Australia on 13 20 50.
- If you have family history or you are concerned that you may have an increased risk of breast cancer, talk to your GP or local family cancer clinic,. Your doctor can help you assess your risk and refer you for additional genetic testing if required.
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What Can I Do To Reduce My Risk Of Developing Breast Cancer Or Ovarian Cancer If I Have A Brca Gene Mutation
Risk-reducing surgery
A prophylactic, bilateral mastectomy, which is the preventive surgical removal of both breasts, can lower the risk of breast cancer by more than 90%. Only about 3% of breast cancers associated with BRCA mutations are diagnosed before age 30, so most women with a BRCA mutation could consider surgery after 30. However, bilateral mastectomy is an invasive and irreversible procedure.
A prophylactic salpingo-oophorectomy, which is the preventive surgical removal of the ovaries and fallopian tubes, can lower the risk of ovarian cancer by approximately 90%. It may also help lower the risk of breast cancer by 50% for women who have not been through menopause. A special procedure to look for microscopic cancer in the ovaries and fallopian tubes is recommended after this surgery. Deciding whether to have preventive surgery to lower your risk of developing breast or ovarian cancer is a very personal decision. Your health care team and genetic counselor can help you understand the risks and benefits, based on your health, type of BRCA mutation, and family history of cancer.
Chemoprevention
Taking oral contraceptives, or birth control pills, for 5 years may lower the risk of ovarian cancer for women with BRCA1 orBRCA2 mutations by up to 50%. However, this must be balanced by a potential slight increase in the risk of breast cancer. Learn more about risk reduction options in this site’s Ovarian Cancer section.
Familial Breast Cancer Research Unit
Read our newsletter to learn about the latest hereditary cancer research updates.
The Familial Breast Cancer Research Unit, led by Tier 1 Canada Research Chair Dr. Steven Narod, is a world leader in the study of inherited cancers. With a particular focus on breast and ovarian cancers, Dr. Narod leads this WCRI team in the study of genetic mutations that are known to increase the risk of many cancers most notably the BRCA1and BRCA2 mutations. Through its extensive research, publications, data collection, genetic testing programs and collaborations, the team has become an internationally renowned leader in identifying and developing effective strategies to prevent and manage these cancers women and families with a high inherited risk.
Virtual Hereditary Cancer Series
This free virtual series, run with The Peter Gilgan Centre for Women’s Cancers at Women’s College Hospital in partnership with the Canadian Cancer Society, highlighted the most relevant advances in hereditary breast and ovarian cancer research. Topics were tailored to women who carry a BRCA1 and BRCA2 mutation. The series ran from January 2021 to November 2021.
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How Do Hereditary Gene Mutations Raise Cancer Risk
Many people wonder how exactly an abnormal gene or combinations of genes could lead to breast cancer, and a brief discussion of the biology is helpful in understanding many of the questions, such as why not everyone who has these mutations develops cancer.
Our DNA is a blueprint or code that is used to manufacture proteins. When the map or code is wrong , it gives the wrong directions for synthesizing a protein. The abnormal protein is then unable to perform its usual job. Not all gene mutations raise the risk of cancer, and in fact, most do not. Mutations in genes responsible for the growth and division of cells, or “driver mutations” are what drive the growth of cancers. There are two major types of genes that, when mutated, can lead to uncontrolled growth known as cancer: oncogenes and tumor suppressor genes.
Several of the genes associated with a higher breast cancer risk are tumor suppressor genes. These genes code for proteins that function to repair damage to DNA in cells , serve to eliminate cells that can’t be repaired, or regulate growth in other ways. The genes BRCA1 and BRCA2 are tumor suppressor genes.
What A Positive Result Means
If your predictive genetic test result is positive, it means you have a faulty gene that raises your risk of developing cancer.
It does not mean you are guaranteed to get cancer your genes only partly influence your future health risks. Other factors, such as your medical history, lifestyle and your environment, also play a role.
If you have one of the faulty BRCA genes, there is a 50% chance you will pass this on to any children you have and a 50% chance that each of your siblings also has it.
You may want to discuss your results with other members of your family, who may also be affected. Staff at the genetics clinic will discuss with you how a positive or negative result will affect your life and your relationships with your family.
You can read more about BRCA1 and BRCA2 in the beginner’s guide to BRCA1 and BRCA2 produced by The Royal Marsden NHS Foundation Trust.
Insurance companies cannot ask you to disclose the results of predictive genetic tests for the majority of policies, but this may change in the future.
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What Are The Screening Options For Hboc
Screening is the use of different tests to find specific types of cancer before signs and symptoms appear. It is important to talk with your health care team about the following screening options, as each person is different:
Screening for women with a BRCA1 or BRCA2 gene mutation
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Monthly breast self-examinations, beginning at age 18
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Clinical breast examinations performed twice a year by a health care team or nurse, beginning at age 25
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Yearly magnetic resonance imaging scans of both breasts, between ages 25 and 29.
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Yearly mammogram and breast MRI, between ages 30 and 75.
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Pelvic examination, trans-vaginal ultrasound, and CA-125 blood test every 6 months, beginning at age 30 to 35. It should be noted, however, that screening is not yet able to find most early ovarian cancers.
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Consideration of prophylactic salpingo-oophorectomy, between ages 35 and 40, and once a woman is done giving birth to children
Screening for men with a BRCA1 or BRCA2 gene mutation
Screening options may change over time as new methods are developed and more is learned about HBOC. Talk with your health care team about appropriate screening tests for you.
Learn more about what to expect when having common tests, procedures, and scans.