About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child.
Genes are particles in cells, contained in chromosomes, and made of DNA (deoxyribonucleic acid). DNA contains the instructions for building proteins. And proteins control the structure and function of all the cells that make up your body.
Most inherited cases of breast cancer are associated with two abnormal genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two). An abnormal PALB2 gene also has been linked to a higher-than-average risk of breast cancer.
People with a strong family or personal history of breast cancer may decide to undergo genetic testing to learn whether or not they have a genetic mutation linked to higher breast cancer risk. A genetic test involves giving a blood sample that can be analyzed to find genetic abnormalities.
To ensure that genetic testing offers the most benefits to the people undergoing it, the American Society for Clinical Oncology (ASCO) has updated its policy statement on genetic testing.
The updated statement was published online on Aug. 31, 2015 by the Journal of Clinical Oncology. Read “American Society of Clinical Oncology Policy Statement Update: Genetic and Genomic Testing for Cancer Susceptibility.”
ASCO is a national organization of oncologists and other cancer care providers. ASCO policy statements give doctors recommendations for treatments and testing that are supported by much credible research and experience.
The updated policy statement focuses on five areas of genetic and genomic testing.
Patient preferences for information on germline and somatic mutations: Germline mutations are genetic abnormalities that exist throughout a person’s body and have been there since the person was conceived. Somatic mutations are genetic abnormalities that happen in almost any cell during a person’s lifetime. Somatic mutations can’t happen in sperm or egg cells, so can’t be passed on to children. For example, an abnormality in a cell that happens because of a person’s exposure to a toxic substance is a somatic mutation.
In many cases, testing labs may find other germline mutations while looking for germline or somatic mutations linked to cancer. These other germline mutations may be linked to other cancers; there also may be no information on many germline mutations.
ASCO recommends that doctors talk to their patients about the possibility that germline mutations besides what’s being specifically looked for may be found by genetic testing and explain the benefits, limits, and risks before genetic testing is done.
Doctors also should ask their patients how much information the patient would like to receive. For example, if a germline mutation is found and doctors don’t know what affect the mutation has, the patient may prefer not to know about the mutation.
ASCO supports research on how to best offer education on genetic testing before the test is done and how to best support patients’ preferences.
Multigene panel testing for cancer susceptibility: When a genetic test looks for more than one abnormal gene, it’s called a “multigene panel” test. In some cases, a multigene panel may find an abnormal gene that wasn’t being looked for, based on a person’s family history. For example, a woman with a strong family history of breast cancer may decide to have genetic testing to see if she has an abnormal BRCA1, BRCA2, or PALB2 gene. Her test results may show that she has another abnormal gene linked to a low risk of pancreatic cancer.
Multigene tests also may find what’s called “variants of uncertain significance” (VUS). VUS are genetic mutations that researchers have no information on. In other words, it’s not clear if these mutations are linked to a disease or not.
Because of knowledge gaps, ASCO recommends that doctors with expertise in cancer risk assessment be involved in ordering and interpreting multigene panel tests that return VUS or abnormal genes not suggested by a person’s personal or family history.
Quality assurance in genetic testing: Analyzing and interpreting genetic test results is complex. ASCO supports high quality standards to help doctors and patients understand the accuracy, benefits, and limitations of genetic tests from different labs. ASCO believes that the current regulations on genetic testing need to be stronger. The policy statement says that for high-risk tests used to identify people at higher risk for cancer should be subject to regulatory review by the U.S. Food and Drug Administration. ASCO also recognizes that these regulations must be designed so they don’t limit access to testing.
Education of oncology professionals: Helping people at high risk for cancer manage that risk and keep it as low as it can be is a core element of being an oncologist. ASCO recommends that oncologists and other healthcare professionals take continuing education classes on cancer risk assessment and management of any known risk. ASCO also recommends that oncology programs incorporate core skills in these areas.
Access to cancer genetic services: ASCO is committed to making sure that people have access to high-quality cancer genetic services and supports these services being covered by insurance. ASCO also opposes any policies that may limit people’s access to genetic testing.
"The sequencing and mapping of the human genome, one of science's greatest modern feats, has launched an age of tremendous discovery and hope in the fight against cancer," said ASCO President Julie M. Vose, M.D., in a statement. "As cancer diagnosis and treatment is becoming more genetically driven, new opportunities and questions are emerging about screening for hereditary cancers. ASCO is releasing this updated policy statement at this critical juncture to ensure that all interested parties thoughtfully consider these concerns as the future of genetic and genomic testing for cancer susceptibility unfolds."
If you and/or some of your family members have been diagnosed with breast cancer, you may be interested in the possibility of genetic testing.
A mutation linked to breast cancer is more likely to run in your family if:
- Many women in your family have had breast and/or ovarian cancer, particularly at a younger age than these cancers typically develop (before age 50).
- Some women in your family have had cancer involving both breasts.
- There is both breast and ovarian cancer in your family.
- Men in your family have had breast cancer.
- There is breast cancer in your family and either male relatives on the same side of the family have had prostate cancer at a young age, or male or female relatives on the same side of the family have had gastrointestinal cancers, such as cancer of the pancreas, gall bladder, or stomach.
- Your family is of Ashkenazi (Eastern European) Jewish descent.
If any of these are true for either side of your family, you may be a candidate for genetic testing. If you’ve been diagnosed with breast cancer, you may want to meet with a genetic counselor before breast cancer surgery. To find a genetic counselor who specializes in family-related cancer risk, talk to your doctor or check with the hospitals and cancer centers in your area.
For more information on genetic testing and counseling, visit the Breastcancer.org Genetic Testing pages.