Screening for colorectal cancer saves lives. But what if you had a crystal ball that tells whether you and your family are more likely to face the disease?
Unfortunately, we don’t have a crystal ball — or its medical equivalent — quite yet, but you can get some insight by knowing your family medical history and whether you have any hereditary genetic conditions like Lynch or FAP syndromes that may increase your risk of colorectal cancer.
How is cancer caused genetically?
While there is still much to learn about this disease, we know it is caused by gene mutations, or changes, that result in cells growing out of control. As you age, gene mutations accumulate, and this is why colorectal cancer most often happens in people over age 50. In most cases, the gene mutations leading to cancer happen at random, although they can be helped along by carcinogens, like the chemicals in cigarette smoke.
Yet, in about 25% of cases, patients have a family history of the disease, signaling a possible genetic condition that causes mutations and increases the likelihood of colorectal cancer at a younger age.
Genetic mutations that increase the risk of cancer can be inherited from parents. Inherited genetic mutations play a role in 5-10% of all cancer cases, including colorectal cancer. Researchers have found more than 50 hereditary cancer syndromes overall. Fortunately, a number of these inherited conditions can be identified through genetic testing, and the results can be life-saving.
The genetic risks of colorectal cancer
Knowing whether you’re at increased risk of genetic mutations that can cause colorectal cancer can help you take precautions to avoid the disease. These are the inherited genetic syndromes relevant to colorectal cancer:
- Familial adenomatous polyposis (FAP), attenuated FAP (AFAP), and Gardner syndrome
- Lynch syndrome (hereditary non-polyposis colon cancer, or HNPCC)
- Peutz-Jeghers syndrome
- MYH-associated polyposis (MAP)
- Li-Fraumeni syndrome
Am I at risk?
There are three subgroups of risk for cancer: sporadic, familial, and hereditary. If you fall into the sporadic group, which means you have no family history of cancer or inherited genetic predisposition, you have about a 1 in 23 chance of getting colorectal cancer. If you have familial risk, meaning an immediate family member has the disease, your lifetime risk increases to 10-20%.
Those who have the highest lifetime risk of colorectal cancer are in the hereditary subgroup. Depending on the particular genetic syndrome, the chances of getting colorectal cancer may be 30-100%.
Special genetic tests can find gene mutations linked to these inherited syndromes. A healthcare provider can help you identify your risk and which type of genetic tests, if any, may be useful. Genetic testing is typically conducted with either a blood or saliva draw and completed in a lab.
Next steps
Colorectal cancer is one of the most preventable and treatable forms of cancer when it’s found early. Screening is the most important thing you can do to prevent colorectal cancer because it finds cancer in the early stages, before it even has the chance to grow or develop.
Talk to your healthcare provider about which screening methods are right for you and when you should begin screening.
Ending the disease
The Colorectal Cancer Alliance, the world’s leading nonprofit organization dedicated to ending colorectal cancer, recently launched Project Cure CRC. The initiative reflects the Alliance’s renewed effort to fund $100 million in expedited, novel colorectal cancer research over the next two years to help improve treatment options and outcomes, and put an end to the disease.
For more information, visit colorectlacancer.org/cure
