Should I have genetic testing for colorectal cancer?

There are two well recognized hereditary syndromes in which cancer can develop in young people. The first is Familial Adenomatous Polyposis (FAP). This is a disease in which there is a mutation of a tumor suppressor gene and affected people develop hundreds to thousands of precancerous polyps in the colon. Unless the colon is removed, 100 percent of these patients will get colorectal cancer, usually by their late 30s. The disease is inherited directly from an affected parent (autosomal dominant inheritance), which means that each child has a 50 percent or one in two chance of inheriting the abnormal gene. If the gene is inherited, the child will eventually develop polyps. The average age for polyp development in this syndrome is the mid-teens, although children as young as eight or 10 sometimes have been found with polyps.

If a family is known to have FAP, the affected parent and at-risk children may be screened for a gene mutation with a genetic test. Children from families who refuse or cannot have genetic tests should start having sigmoidoscopies or colonoscopies at about 10 or 12 years old and every six to 12 months to look for the presence of polyps. Once numerous polyps start developing, surgery is planned. The good news about this disease is that the surgical options are very good. The bowel is put directly back together and no bag is necessary. People move their bowels normally.

The other inherited disorder is Hereditary Non-Polyposis Colorectal Cancer (HNPCC). In this syndrome cancers also occur early and develop from polyps. But here, there are not the hundreds of polyps seen in FAP. The disease presents at a later age, too. The standard recommendation is colonoscopy in at risk children of affected families beginning at age 25 and repeated every two years. Genetic testing may also be helpful here.
There are specific recommendations for children in families with high rates of colorectal cancer, but the specific syndrome must be known. It is very important for children from families like these to be seen by experts who have experience with these syndromes and in institutions where genetic counseling and testing services are available.

It is possible, although quite rare, for sporadic colon cancer to occur in young people outside of those affected by FAP or HNPCC.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.