Hereditary Cancer
All cancer is genetic, but only some cancer is hereditary. Cancer occurs when the normal mechanisms that control cell growth fail because of a genetic mutation. Without proper control mechanisms, healthy cells can grow too rapidly or fail to correct changes, leading to cancer. Some people are born with mutations inherited from a parent; others acquire a mutation during their lifetime.
In fact, for most people with cancer, the cancer-causing gene mutations result from acquired changes that happen over the course of a lifetime. Acquired mutations commonly arise in the natural process of aging or due to environmental factors, such as sun exposure or smoking. These mutations happen randomly and are not passed down from parents to children. Cancer caused by acquired mutations is called sporadic cancer.
On the other hand, hereditary cancers can occur when individuals are born with an inherited genetic mutation that predisposes them to an increased risk for cancer. While not everyone with an inherited genetic mutation will develop cancer, the risk is significantly increased compared to the average population risk. A person with an inherited gene mutation also has a 50% chance of passing it down to each child.
About 5-10% of cancers are hereditary. About 70% of cancers are sporadic, or due to an acquired mutation. The remaining 20% of cancers fall into a category called familial, which means that there seems to be some pattern of cancer within a family, but no specific mutation has been identified.
Mutations in the BRCA1 and BRCA2 genes are about 10 times more common in the Jewish population than the general population, affecting about 1 in 40 individuals of Ashkenazi Jewish descent (compared to about 1 in 400 individuals in the general population). Learn more about BRCA mutations. You can also learn more about Lynch syndrome and other hereditary cancers in the Jewish community.
Meeting with a genetic counselor is a good first step if you are concerned about your risk for hereditary cancer. A genetic counselor can help you collect your family health history and asses your personal and family risk of certain hereditary cancers. If necessary, a genetic counselor can also help you work with your doctor to make a care plan to manage your risk.
Genetic counselors are clinical professionals with advanced training in medical genetics and counseling. They provide education and personalized support for individuals and families affected by – or at increased risk for – genetic disorders, including hereditary cancers. Genetic counselors can:
- Assess risk
- Help individuals collect and make sense of their family health history
- Help individuals think through the benefits and drawbacks of genetic testing and make informed decisions
- Interpret test results
- Discuss available options and provide resources
Genetic counseling is essential for all people considering BRCA cancer risk testing. Learn more about genetic counseling.
Medical geneticists are doctors who specialize in genetics. In addition to providing education and personalized support, they may also help to identify and treat genetic disorders in an individual or family. Medical geneticists may specialize in cancer genetics, or in other sub-specialties such as metabolic disorders.
Genetic testing can identify patients who have genetic mutations that may significantly increase a person’s risk of developing a disease, such as cancer. For people who have received a cancer diagnosis, genetic testing may help to inform treatment strategies. Genetic tests require either a blood draw or a saliva sample.
The Norton & Elaine Sarnoff Center for Jewish Genetics recommends meeting with a genetic counselor before receiving a cancer genetic test. A genetic counselor can discuss the benefits and risks of genetic testing, as well as the implications of positive or negative results, and help you think through any factors that may influence your decision about whether you want to proceed with testing.
Genetic testing for hereditary cancers involves more than the average blood test because it may raise issues of:
- Test-related anxiety — what will you do with the information?
- Privacy and confidentiality — who has access to the information?
- Genetic discrimination — what are the myths and realities
- Psychological effects within families — how will your genetic test results affect your family members, and how do they feel about you being tested?
Genetics professionals recommend people seek counseling both before and after testing to prepare for the test and understand results.
The Norton & Elaine Sarnoff Center for Jewish Genetics cautions regarding the use of direct-to-consumer (DTC) testing such as the 23andMe test to determine one’s personal risk for hereditary cancer. Those who consider using such tests, or who receive such test results, should understand these key points:
- The results given by these tests are extremely limited, do not cover all genes that can predispose to genetic conditions, and are potentially misleading. The raw data files of these tests have been shown to provide test results that are falsely positive 40-50% of the time.
- Those who receive positive test results without assistance from a genetic counselor or qualified physician are not likely to have adequate preparation to understand their risk or evaluate appropriate preventative measures.
- Those who receive negative test results may not understand their remaining risks for hereditary or non-hereditary cancer. Only about 10% of cancers are directly linked to mutations such as those found in the BRCA1/BRCA2 genes.
- In almost all cases, physicians and genetic counselors who see patients regarding DTC results will and should recommend that patients get more comprehensive testing.
Read the Sarnoff Center’s full statement on direct-to-consumer cancer testing.
Genetic testing can help you and your doctor better understand your health risks so that together you can determine a management plan that is right for you. This may include more frequent examinations, blood tests, imaging, medications, or risk-reducing surgeries.
While many people feel empowered when they receive genetic test results, testing may not be right for everyone. For example, some people may find that knowing about a mutation or cancer predisposition causes increased anxiety. A genetic counselor can help you think through the implications of testing and help you make an informed decision. If you decide not to undergo genetic testing, you may talk to your doctor about whether increased cancer surveillance is appropriate for you.
There are various approaches someone with a BRCA mutation can take to reduce their risk, including increased surveillance and screenings, medication, and surgeries. There is no right approach; only what is right for each person. Furthermore, an individual’s approach to risk management may change throughout their life. Your doctor can help with personalized risk reducing recommendations. Learn more about BRCA risk management strategies.
