Colon cancer is the result of small growths in the colon developing the ability to spread throughout other tissues in the body. Some patients have a genetic predisposition to developing colon cancer, which can result from certain hereditary diseases. Patients with a family history of colon cancer may want to be tested for these conditions.
Colon Cancer and Polyps
Three kinds of growths can appear in the colon, the National Cancer Institute explains: non-neoplastic polyps, adenomatous polyps and cancer. Patients who have had adenomatous polyps have an increased risk of developing colon cancer. This could be that patients who get these growths are more susceptible to genetic changes that cause colon cancer, or it could be that adenomatous polyps are a precursor to colon cancer. Adenomatous polyps are often treated as growths that will turn into cancer if not treated. Many of the conditions that indicate a predisposition for colon cancer lead to the development of polyps.
Colon-Specific Syndromes
Two genetic conditions specifically increase a patient's risk of developing colon cancer, the National Human Genome Research Institute explains. Familial Adenomatous Polyposis is a condition caused by mutations in the APC gene. This causes patients to develop many polyps in their colon, and patients with Familial Adenomatous Polyposis have a nearly 100 percent chance of developing colon cancer by the age of 40. Lynch syndrome, also known as hereditary nonpolyposis colon cancer, is a disorder resulting from mutations in one of five different genes. Patients with this condition do not develop colon polyps, but they do have an estimated 80 percent risk of developing colon cancer at some point in their lives.
Other Disorders
One condition, known as Turcot syndrome, predisposes patients to developing adenomatous polyps and colon cancer; patients with this condition are also at an increased risk of developing brain tumors. The American Cancer Society notes that Turcot syndrome occurs in two forms that can either cause medulloblastomas or glioblastomas, both of which are different kinds of brain tumors. Peutz-Jeghers syndrome can lead to patients being predisposed to developing a variety of different cancers, including colon cancer. This condition can also cause polyps to develop within the digestive tract.
Testing
People who have a family history of colon cancer may wish to undergo genetic testing to determine if they have any of the genetic abnormalities that are known to cause a predisposition to developing colon cancer. These tests, the National Human Genome Research Institute notes, generally involve looking at the DNA in the patient's white blood cells. These tests cannot identify all genetic mutations that can lead to colon cancer, but they are designed to catch many of the common ones.
Preventive Care
Identifying genetic mutations that predispose a patient to developing colon cancer does not mean future cases of colon cancer can be cured. It does, however, allow the patient to receive more regular tests to attempt to detect colon cancer, or polyps, in their early stages. Catching the cancer early dramatically increases the patient's chances for long-term survival. In some cases, patients may have their colon removed as a preventive measure, which will keep the patient from developing colon cancer.
