When a mother is diagnosed with colon cancer, her children often wonder about their own risk. Family history plays a role in an individual’s likelihood of developing this disease, guiding proactive health measures.
Understanding Family History and Colon Cancer
Colon cancer can arise from various factors, with family history being significant. Most cases are “sporadic,” occurring without a clear inherited pattern and typically affecting individuals over 60. However, 25% to 35% are “familial,” appearing more frequently within families, even without a specific gene mutation. A smaller proportion, about 5% to 10%, are “hereditary,” directly linked to inherited gene mutations.
Having a first-degree relative, such as a parent, sibling, or child, with colon cancer increases an individual’s risk. This risk escalates further if the relative was diagnosed at a younger age, specifically before 50. For instance, if a first-degree relative was diagnosed with early-onset colorectal cancer, an individual is six times more likely to develop it before age 50. The presence of pre-cancerous colorectal polyps in a first-degree relative also elevates risk.
Key Hereditary Colon Cancer Syndromes
Certain inherited genetic conditions significantly increase the risk of developing colon cancer. Lynch syndrome, also known as Hereditary Nonpolyposis Colorectal Cancer (HNPCC), is the most common inherited cause of colorectal cancer. It results from germline mutations in specific mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, and PMS2, or sometimes the EPCAM gene. Lynch syndrome is typically inherited in an autosomal dominant pattern, meaning a 50% chance for each child to inherit the altered gene if one parent carries it. These genes are normally responsible for correcting DNA replication errors; when mutated, errors accumulate, increasing cancer risk.
Another notable hereditary condition is Familial Adenomatous Polyposis (FAP). FAP is characterized by the development of hundreds to thousands of adenomatous polyps in the colon and rectum, usually beginning in adolescence. These polyps carry a nearly 100% risk of becoming cancerous if left untreated. FAP is primarily caused by germline mutations in the APC gene, located on chromosome 5q21-22, and is inherited in an autosomal dominant manner.
Assessing Your Personal Risk and Screening Guidelines
Evaluating personal risk for colon cancer involves considering the specific details of your family history. Factors such as the number of affected relatives, their relationship to you (e.g., parent, sibling), and their age at diagnosis are important. A healthcare provider can use this information to determine increased risk.
For individuals with a family history of colon cancer, screening recommendations often differ from standard guidelines. While average-risk individuals typically begin screening around age 45, those with a first-degree relative diagnosed with colon cancer may need to start earlier. A common guideline suggests initiating colonoscopy screening at age 40, or 10 years earlier than the youngest age of diagnosis in the family, whichever comes first. For example, if your mother was diagnosed at 48, you would start screening at 38. Colonoscopy is the preferred screening method for those with a family history; if results are negative, it may be repeated every five years.
For very strong family histories, especially those suggesting a hereditary syndrome like Lynch syndrome or FAP, screening might begin even earlier, sometimes in childhood or early adulthood, and occur more frequently. Genetic counseling and testing can be valuable options for individuals with multiple close relatives affected by colon cancer, or if cancers occurred at a young age. These services can help identify specific inherited gene mutations, guiding more personalized surveillance and management strategies.
Lifestyle Factors and Risk Reduction
Even with a family history, lifestyle choices can influence the overall risk of colon cancer. Maintaining a healthy body weight is beneficial, as excess weight is linked to an increased risk of colorectal cancer. Regular physical activity also helps reduce risk; at least 30 minutes of moderate activity daily is often recommended.
Dietary habits play a role in risk reduction. Consuming a variety of fruits, vegetables, and whole grains provides fiber, vitamins, and antioxidants that may protect against cancer. Limiting the intake of red and processed meats is also advised, as these have been associated with an increased risk of colorectal cancer. Additionally, moderating alcohol consumption and avoiding smoking are important steps to lower colon cancer risk.