Study: No new high-risk breast cancer genes here
|At a glance||Questions for your doctor|
These studies are about:
Identifying new variants associated with increased risk of breast cancer.
Why are these studies important?
Mutations are changes in the of genes that cause the gene to stop working normally. Inherited mutations in certain genes (e.g. , , , and others) greatly increase the risk for cancer, and can cause cancer to run in families. These mutations explain only a fraction of all inherited breast cancers.
In contrast, these two reports are about a different type of change known as a (or ). A is a common variation in a single base-pair of . There are roughly 10 million SNPs in the human genome. Most commonly, SNPs are found in the portion of between genes. Scientists do not completely understand how SNPs affect gene function. Scientists believe that these gene variations can have small effects on the risk for some diseases such as cancer.
One study identified 65 SNPs that are associated with overall breast cancer risk. The second study identified 10 SNPs associated with increased risk, specifically of receptor negative (ER-negative) breast cancer. Between the two studies, a total of 72 SNPs were identified.
What does this mean for me?
Dr. Elizabeth Swisher, Professor, Department of Ob/Gyn, and Director, Division of Gynecologic Oncology at the University of Washington, and member of FORCE’s Scientific Advisory Board cautioned, “At the present time, these studies do not lead to any changes in recommendations for screening or prevention of breast cancer in women with or without or other inherited breast cancer predisposing mutations.”
It is important to note that although these new SNPs are associated with increased breast cancer risk, they do not directly cause the disease like mutations in known breast cancer genes such as , , , , and others. Instead, these SNPs are "tagging along" with some other factor that may be increasing breast cancer risk. They are like the edge pieces of a puzzle, but other pieces are still missing. Additional research is need to find the remaining pieces of the genetic puzzle. Only then can they connect them to other information or analyze them in new ways. With a better understanding of how these SNPs contribute to breast cancer risk, experts may use that information to more accurately predict a person’s risk.
Dr. Otis Brawley, chief medical officer of the American Cancer Society, who was not involved in the research but interviewed by CNN, described the new research as "not earth-shattering." It is "most important for us nerds," he said, but less so for the general public.
An expert in cancer genetics, such as a genetic counselor, can help you understand your personal breast cancer risk.
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Michailidou K, Lindström S, Dennis J, et al. “Association analysis identifies 65 new breast cancer risk loci.” Nature. 2017. 551(7678):92-94.
Milne RL, Kuchenbaecker KB, Michailidou K, et al. “Identification of ten variants associated with risk of estrogen-receptor-negative breast cancer.” Nature Genetics. 2017. 49(12):1767-1778.
FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.
This article is relevant for:
People with a family history of breast cancer but no known inherited mutation
This article is also relevant for:
healthy people with average cancer risk
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IN-DEPTH REVIEW OF RESEARCH
Scientists sometimes try to identify common variations called single nucleotide polymorphisms (SNPs) in the human genome that maybe associated with a particular disease. These genome-wide association studies (GWAS) are conducted in two groups: people with the disease being studied (e.g. breast cancer) and similar people without the disease. from participants in each group is scanned on automated laboratory machines and the from the two groups are compared for differences. If certain SNPs are found to be significantly more frequent in people with the disease compared to people without the disease, the SNPs are said to be "associated" with the disease. Newly identified SNPs can serve as pointers to a region of the human genome where disease-causing problems in the may reside.
Much of our does not actually get transcribed into proteins. Because these GWAS studies look at SNPs scattered throughout the human genome– most outside of the actual portion of the that codes for proteins – the SNPS identified through GWAS studies rarely provide clear answers about how they contribute to disease development. Although GWAS studies have provided clues for several different diseases, they do not always lead to changes in how patients are managed.
Two recent GWAS studies, “Association analysis identifies 65 new breast cancer risk loci” published in Nature and “Identification of ten variants associated with risk of estrogen-receptor-negative breast cancer” published in Nature Genetics, together identified 72 SNPs in the human genome that are associated with breast cancer risk.
Researchers of this study wanted to know:
If they could identify common genetic changes that influence breast cancer risk.
Population(s) looked at in the study:
The study published in Nature compared genome data from more than 100,000 breast cancer patients and a similar number of cancer-free controls.
The study published in Nature Genetics compared genome data from 21,468 patients with ER-negative breast cancer and 100,594 controls, as well as 18,908 mutation carriers. ( mutation carriers are more likely to develop receptor-negative disease).
The Nature report identified 65 new genetic SNPs associated with increased breast cancer risk, while the Nature Genetics report identified 10 new SNPs (3 of which overlapped with the 65) associated with increased risk of ER-negative disease. These 72 new SNPs were most commonly located in non-coding regions of the genome which are outside of or away from coding regions which contain genes. Many of these SNPs likely regulate (turn on or off) genes, although how they do this is currently unknown.
The amount of increased risk caused by each individual is uncertain. However, because they are common and their impacts multiply together, the collective effect may be considerable. For instance, the researchers predicted that the breast cancer risk among women who carry many of these SNPs—1% of women studied—is more than 3 times greater than the rest of the population.
These studies were conducted with women who were primarily of European ancestry and it is likely that SNPs associated with breast cancer that are common in non-European populations were missed. To find these, similar studies in Africans, African Americans, Latinas, Chinese and other populations are ongoing.
It is possible that patterns in the inheritance of these SNPs may help us to understand why some women are predisposed to breast cancer. Researchers hope that identifying these SNPs may lead to a better understanding of specific genes and mechanisms that are involved in the development of breast cancer. The biggest problem in taking advantage of GWAS information is our limited understanding of why and how these common variations in the human genome might increase breast cancer risk. These changes in sequence are not mutations found in coding regions of genes. It will take time and effort to understand exactly how they contribute to disease risk as well as the best way to manage these increased risks.
At the time of this review, this research does not change expert recommendations for risk assessment and risk management for breast cancer. Researchers will now work toward using these SNPs and other factors to better predict breast cancer risk. With additional research, it may be possible to use the SNPs identified in these studies to categorize more women into groups based on their breast cancer risk. If successful, these could be incorporated into tests that would allow women with increased risks to receive screening and prevention that is tailored to their personal risk.
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The National Comprehensive Cancer Network has guidelines on who should undergo genetic counseling and testing. If you have been diagnosed with breast cancer, you should speak with a genetics expert about genetic testing if any of the following apply to you:
- You have a blood relative who has tested positive for an
- You have any of the following:
- Breast cancer at age 50 or younger
- Male breast cancer at any age
- Ovarian cancer at any age
- at any age
- Two separate breast cancer diagnoses
- Eastern European Jewish ancestry and breast cancer at any age
- Lobular breast cancer and a family history of diffuse gastric cancer
- For treatment decisions for people with breast cancer or people with early , breast cancer who are at high-risk for recurrence
- Testing of your tumor shows a mutation in a gene that is associated with
- You have one or more close family members who have had:
- Young-onset or rare cancers
- Breast cancer at age 50 or younger
- Male breast cancer, ovarian cancer, pancreatic cancer, or cancer at any age
- Two separate cancer diagnoses
- prostate cancer or cancer that is high-risk or very-high-risk group.
The American Society of Breast Cancer Surgeons (ASBrS) released guidelines in 2019 that recommend all women diagnosed with breast cancer have access to genetic testing for inherited mutations in breast cancer genes.
If you are uncertain whether you meet the guidelines above and you are interested in or considering genetic testing, you should speak with a cancer genetics expert.
- What is my risk for breast cancer?
- Should I speak with a genetic counselor?
- Is my cancer due to an inherited genetic mutation?
- Do these studies change how I should be screened?
Below are clinical trials that include genetic counseling and testing.
- NCT02665195: Registry Of MultiPlex Testing (PROMPT). PROMPT is an online research registry. The goal of PROMPT is to help researchers to better understand the risks that are linked to mutations in less well-studied genes.
- NCT02620852: WISDOM Study: Women Informed to Screen Depending on Measures of Risk offers women age 40-74 the opportunity to undergo risk assessment and genetic testing in order to determine the best breast screening options based on their situation.
- NCT04476654: Improving Uptake of Genetic Cancer Risk Assessment in African American Women-Video. This study looks at the usefulness of intervention with a culturally-tailored video to improve uptake of genetic counseling in Black women who are at increased risk of .
- NCT05694559: Connecting Black Families in Houston, Texas to Genetic Counseling, Genetic Testing, and Cascade Testing by Using a Simple Genetic Risk Screening Tool and Telegenetics. This study will provide genetic testing to 150 Black individuals and families and provide genetic counseling and risk reduction resources to individuals with a mutation linked to increased cancer risk.
Other genetic counseling or testing studies may be found here.
Who covered this study?
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