If your doctor finds multiple polyps during a colonoscopy, it may be a sign that you have a hereditary syndrome that increases your risk of developing rectal cancer. About 5 to 10 percent of rectal cancer cases are due to specific changes in the genes that may be passed from parents to children. Our Clinical Genetics Service offers counseling and education about the risk of hereditary forms of rectal cancer, as well as genetic testing for you and your family members.
During genetic testing, we may take a sample of tissue from your blood, a polyp, or a tumor (if you already have rectal cancer). We’ll use this to look for changes in your genes that are associated with hereditary syndromes that cause the disease. If we discover a mutation, this can help your treatment team determine which condition you have and, in turn, affect your treatment.
Our knowledge of genetic mutations continues to increase rapidly. In some cases, we may find a mutation that we don’t yet understand but that still might put you at higher risk for hereditary cancer. If this happens, our counselors may recommend you and your family members have screening more often.
Learn more about the hereditary disorders that increase your risk of developing rectal cancer.
Familial Adenomatous Polyposis
Familial adenomatous polyposis (FAP) consists of many precancerous polyps — possibly hundreds or thousands — in the colon and rectum. A milder form of FAP involves a smaller number of colorectal polyps.
Lynch syndrome (formerly known as hereditary nonpolyposis colorectal cancer) is associated with an increased risk of colon and rectal cancer, as well as endometrial, ovarian, gastric, urinary tract, brain, and pancreas cancers, among others.
In MYH-associated polyposis, multiple precancerous polyps are present in the colon and rectum, similar to the amount seen in the milder form of FAP.
Hyperplastic Polyposis Syndrome
In hyperplastic polyposis syndrome (HPS), multiple hyperplastic polyps develop in the colon and rectum. Currently, there is no gene mutation known to be associated with HPS.