Colorectal cancer is one of the most common cancers in the United States, with risk factors that include age, lifestyle, and family history. While many cases develop sporadically, meaning they occur without a clear inherited cause, genetics can significantly influence a person’s risk. In this blog, the team of board-certified colorectal surgeons at Piedmont Colorectal Associates discusses how genetic factors contribute to colorectal cancer so that patients can adopt preventive measures and undergo earlier screenings when necessary.

Inherited vs. Acquired Genetic Mutations

Genetic mutations that increase colorectal cancer risk fall into two categories: inherited (germline) mutations and acquired (somatic) mutations. Inherited mutations are passed from parents to children and can significantly increase the likelihood of developing colorectal cancer. These mutations are present in every cell of the body and can be detected through genetic testing. Acquired mutations, on the other hand, develop over time due to environmental factors, lifestyle choices, and normal cellular aging.

Hereditary Colorectal Cancer Syndromes

Approximately 5–10% of colorectal cancer cases are linked to hereditary syndromes. The two most well-known inherited conditions associated with colorectal cancer include:

• Lynch Syndrome (Hereditary Nonpolyposis Colorectal Cancer, or HNPCC) – This is the most common hereditary colorectal cancer syndrome, accounting for about 3–5% of cases. It results from mutations in DNA mismatch repair genes (MLH1, MSH2, MSH6, PMS2) that prevent cells from correcting errors during replication. People with Lynch syndrome have a higher risk of developing colorectal cancer, often before the age of 50. They may also be at increased risk for other cancers, such as endometrial, ovarian, and stomach cancer.
• Familial Adenomatous Polyposis (FAP) – This rare but serious condition is caused by mutations in the APC gene, leading to the development of hundreds to thousands of polyps in the colon and rectum, often beginning in adolescence. If untreated, nearly all individuals with FAP will develop colorectal cancer by their 40s.

Does Family History Increase Your Risk?

Even without a known hereditary syndrome, having a close relative (parent, sibling, or child) with colorectal cancer doubles the risk of developing the disease. The risk increases further if multiple relatives are affected, especially if they were diagnosed before age 50. This suggests a possible genetic predisposition, even if a specific mutation is not identified.

The Importance of Genetic Testing and Early Screening

For individuals with a family history of colorectal cancer or known hereditary syndromes, genetic counseling and testing can provide critical insights into their risk level. Regular colonoscopies, beginning earlier than the general screening age of 45, can detect and remove precancerous polyps before they become cancerous.

Take Control of Your Colorectal Health

If you have a family history of colorectal cancer or are concerned about your genetic risk, Piedmont Colorectal Associates in Atlanta, GA offers expert guidance and advanced screening options. Our specialists can help determine the right preventive measures for you. Schedule a consultation today by calling (404) 351-7900.