Your Genes & Cancer
More and more, researchers are discovering what factors may make cancer more likely. For example, new data reveals the role fat-laden diets, lack of physical activity and other lifestyle choices might play in the development of certain cancers and other diseases. At the same time, we now know that about 1 in 10 cancers are somewhat beyond our control— due to harmful changes (called mutations) in the genes we are born with.
These faulty genes, which are passed from one generation to the next, allow abnormal cells to grow. As these “errors” accumulate, it can make cancer more likely. Certain genetic mutations are linked to specific types of cancer.
For example, women who have a mutation in one of the BReast CAncer (BRCA) genes are much more likely to get breast or ovarian cancer in their lifetime compared to other women. Harmful changes in our genes have also been tied to pancreatic, colorectal, uterine, stomach, prostate and other types of cancer. Hereditary cancers also tend to strike at younger ages.
A hereditary cancer develops as a result of a gene mutation that is
passed down from a parent to a child. It is important to remember that
cancer is not inherited, only the gene that increases the risk of
The good news is that as scientists learn more about individual and groups of genes and how they can affect an individual’s risk of cancer, it provides more opportunities to prevent cancer or find it earlier through evidence-based screenings. Genetic counseling and testing are also becoming more widely available, especially for people who develop cancer at a young age or who have a strong family history.
While genetic testing may appear to be straightforward, through a routine blood draw, the information gleaned from genetic testing is only helpful if ordered and interpreted correctly. Of course, the process of recounting the family history of cancer and learning that you may be at increased risk can be an emotional and difficult process, regardless of the results.
Some people want to know; others are unsure, and worry about what they will do with the information. But knowing information about your cancer risk can be life-saving; not just for you, but for other members of your family too.
In addition to taking steps to stay healthy overall, people with a known mutation are offered frequent, earlier screenings and medical options to help stay on top of and lower their risk of certain cancers, which ordinarily would not be prescribed.
The Most Common Hereditary Cancers Are:
Genetic Counseling & Testing
A genetic counselor, someone with special training in how cancer occurs in families, can help determine whether you or members of your family would benefit from cancer genetic testing.
Because some cancers are associated with several different hereditary mutations or disorders, it is critical that someone with advanced training in genetics assesses your personal and family history to assure 1) the right test is ordered and 2) the results are interpreted correctly.
Genetic testing typically involves a blood or saliva sample. A special analysis in the lab can detect DNA changes that suggest a mutation. If more than one family member is interested in being tested, it is usually best to start testing with a person who has (or had) cancer, if possible.
Once a DNA change (mutation) has been found, that same mutation can be tested for in other family members. Genetic tests do not always give a simple yes or no, so it is important to work with a genetic counselor.
If you are interested in genetic counseling and testing, talk with your health care team.
Benefits of Knowing
There are benefits to knowing if you carry a mutation. The results can:
Provide a better measure of your cancer risk
Allow you to tailor cancer screening as needed
Help guide you in choosing options, such as preventive surgery or medications, to reduce the chances you will develop cancer
Benefit others in your family
If you already have cancer or have a family history of cancer, knowing whether or not you carry a mutation will shape future treatment, as well as how intensely you should be monitored with screenings and exams. It will also help determine your risks and medical management options for others cancers.
Many people find it helpful to seek additional support from other people who have a mutation, support groups, or a psychologist to help them sort through their feelings and medical choices.
Examples of Genetic Mutations
Mutations in the BRCA1 or BRCA2 gene make breast and ovarian cancer more likely. For more information, read CSC’s: Frankly Speaking About Cancer: BRCA1/BRCA2 Mutations
Lynch Syndrome, which is also called Hereditary Nonpolyposis Colorectal Cancer (HNPCC), is caused by mutations in five specific genes. Someone with this genetic disorder has a much higher chance of being diagnosed with early-onset colorectal cancer.
Lynch syndrome is also associated with an increased risk for cancers of the uterus, ovary, stomach, small intestine, biliary system, pancreas, and urinary tract. For more information, read CSC’s: Frankly Speaking About Cancer: Lynch Syndrome
Familial Adenomatous Polyposis
There are other rare forms of hereditary colon cancer. One of these is called Familial Adenomatous Polyposis (FAP). In this condition, young adults develop hundreds or thousands of polyps in the colon. If not treated, these polyps will likely develop into a cancer by the time these individuals reach their 40-50s.
There are two other, similar but potentially milder hereditary colorectal syndromes, known as Attenuated Familial Adenomatous Polyposis (AFAP) and MYH-Associated Polyposis. These syndromes have many of the same features of classic FAP, but often present with fewer polyps.
There are several types of colon polyps. Individuals with more than 5 hamartomatous polyps should be evaluated by a genetic counselor.
A Refresher on Our Genetics
Genes are in every cell in our body. They are contained in structures called chromosomes, which are found in the center of a cell (nucleus). We have 23 pairs of chromosomes— 46 altogether. One chromosome in each pair comes from our father, and the other comes from our mother.
Each chromosome, in turn, is made up of thousands of genes, which are coded segments of DNA that like chromosomes also come in pairs. A change in the sequence of the DNA that makes up the gene can cause the gene to stop functioning. These genetic changes are called mutations. Inheriting a gene mutation does not necessarily mean that person will develop cancer, but increases their risk to develop cancer.
Protection Against Genetic Discrimination
In 2008, the United States Congress passed into law a bill making genetic discrimination illegal. The Genetic Information Nondiscrimination Act of 2008, also referred to as GINA, is a federal law that protects Americans from being treated unfairly because of differences in their DNA that may affect their health. The law prevents discrimination from health insurers and employers.
In addition, as part of health care reform in 2010, group health plans can no longer deny insurance based on preexisting conditions and cannot increase premiums based on health status.
Finding a Genetic Counselor
These days, many hospitals have genetic counselors on staff. If there is not one in your area, a company called Informed DNA provides genetic counseling over the phone. They can help coordinate a blood draw in your area, if genetic testing is necessary. Here are some resources to help find a genetic counselor near you: