Family History & Colon Cancer Screening

Colon cancer is often discussed under the general term "colorectal cancer," which refers to cancers occurring in both the rectum and colon, because of the similar characteristics. Excluding skin cancers, colorectal cancers are the third most common type in the United States and the second-leading cause of cancer-related deaths. In 2009, 106,100 new colon cancer cases alone were diagnosed.

Formation

• Colon cancer begins in the innermost layer of colon tissue and spreads inward. For most, colon cancer takes years to form from polyps, which are noncancerous growths. Adenomatous polyps in the colon have the potential to turn cancerous, while hyperplastic polyps usually do not. According to the American Cancer Society (ACS), however, some physicians believe the presence of hyperplastic polyps indicates an increased risk of developing the adenomatous version, especially when they occur in the ascending colon.

Types

• Adenocarcinomas, or cancerous growths that occur in the mucus-producing glands of the colon and rectum, account for 95 percent of all colorectal cancers. The other 5 percent come from carcinoid tumors that develop from specialized cell-producing hormones, gastrointestinal stromal tumors that develop from specific interstitial cells, and lymphomas, which typically occur elsewhere in the body but can develop in the colon.

Screening Practices

• According to the American Cancer Society, the death rate from colorectal cancers has decreased since 1990, largely due to improved screening methods and the early removal of polyps. Screening tests that find both polyps and cancer in the colorectal system include flexible sigmoidoscopy, double-contrast barium enema and CT colonography, or virtual colonsocopy. The ACS recommends those over 50 get a screening every five years. Tests that only detect cancer and that can be performed yearly include fecal occult blood test, fecal immunochemical test and stool DNA test.

Family History

• The ACS reports that four in five patients with colorectal cancer have a family member with the disease. Those with a first-degree relative (parents, siblings or children) with a history of colorectal cancer have twice the risk of getting it. The risk is higher if more than one first-degree relative has that history or if someone in the family suffered the disease at an early age. Physicians usually recommend those with a family history of colorectal cancers to start screenings earlier than age 50 and to get them more often.

Specific Familial Conditions

• Specific conditions that are familial or genetically linked increase an individual's risk for colorectal cancers, and these should be taken into consideration when determining screening schedules. Some 5 to 10 percent of those with these diseases have inherited genes causing the cancers. These include familial adenomatous polyposis and hereditary nonpolyposis colon cancer, or Lynch Syndrome. Turcot syndrome and Peutz-Jeghers syndrome are other familial and rare conditions that increase the risk of colorectal cancers.