Colorectal cancer is the third most common cancer (excluding skin cancers) and the second leading cause of cancer-related deaths in the United States. Each year about 150,000 people are diagnosed with the disease.
Risk factors for colorectal cancer include age (most cases occur in people over 50), ethnicity (African Americans and Ashkenazi Jews have particularly high rates of the disease), a personal history of colon polyps or colorectal cancer, and the presence of inflammatory bowel disease (Crohn’s disease or ulcerative colitis). Obesity, physical inactivity, smoking and heavy drinking have also all been associated with increased risk for colorectal cancer.
Genetics contribute to a person’s colorectal cancer risk, although non-genetic factors seem to play a larger role. About 5% of people with colorectal cancer, however, develop the disease as a result of either familial adenomatous polyposis (FAP) or Lynch syndrome, two cancer syndromes caused by serious genetic mutations.
Anyone with a family history of colorectal cancer should talk to their health care professional about what screening procedures, and possibly what genetic tests, are right for them.
Research to find common genetic variants associated with colorectal cancer risk has yielded several good associations, but together they explain only a small part of the genetic contribution to the disease. There are probably many more variants with small effects left to be found, as well as rare variants with larger effects. 23andMe customers can see their results for three replicated SNP associations in the Colorectal Cancer Research Report. Spittoon posts addressing colorectal cancer can be found here, here, here and here.
Learn More About Your Risk
Several online tools are available to help you get a better idea of your risk for colorectal cancer.
- National Cancer Institute
- Washington University School of Medicine Siteman Cancer Center
- My Family Health Portrait – a free online tool provided by the Surgeon General that can help you assemble your family’s health history
You can contact the following organizations to learn more about colorectal cancer and find out how to get involved in Colorectal Cancer Awareness Month.