TedEd-26

Who's at Risk for Colon Cancer?

If you were to lay your digestive tract out in a straight line, it would form a tube spanning nearly ten
meters. The last 1.5 meters of that are called the colon, or large intestine. Cells in this organ's lining
constantly renew themselves, but the genes that moderate this process occasionally go awry,leading to the excessive growth of new cells. That results in small growths or abnormal clumps ofcells called polyps. The majority of these polyps won't do any harm, but some can becomecancerous when their cells begin to grow and divide rapidly, projecting further into the colon. At thatpoint, they can transform into colon cancer, one of the most prevalent and preventable forms ofcancer in the world. That's a slow process: though growth times vary, it often takes around ten years
for a small polyp to grow and develop into a cancerous one. We don't know exactly what causes themajority of colon polyps and colon cancers. We do know in general that colon cancer involves theactivation of what's called oncogenes in the polyp, and/or the loss of tumor-suppressor genes thatTedEd-26

Who's at Risk for Colon Cancer?

usually keep cancer cells in check. Most cells have proto-oncogenes that help them grow. When aproto-oncogene mutates, or there are two many copies of it, it can become a permanently active
oncogene with cells that grow out of control. While we don't yet know exactly what underlying
factors cause these changes, experts suspect a combination of both environmental and inherited
genetic factors. In the worst cases, when cells within polyps divide and spread unchecked, they
eventually break through the lining of the colon. Lymph and blood vessels carry those cells all overthe body, and they can go on to form tumors.
Despite these challenges, there's a solution. We've become extremely good at detecting andremoving offending polyps before they can cause cancer. This happens through a process calledscreening, and when we do it regularly, we can prevent many cases of colon cancer. So, who's atrisk? Most cases occur in people aged 50 years or older. This group is considered at average riskfor colon cancer or colon polyps. There's also a higher risk group that includes people with personalor family histories of colon polyps or cancer, and those who suffer from inherited genetic
syndromes, or inflammatory diseases, like Crohn’s disease and ulcerative colitis. So the best age toinitiate screening varies from person to person. If you have access to healthcare, it's best to consulta doctor to find out when you should begin. Screening can be done with various tests.
Colonoscopy involves a long, thin, flexible tube that's fitted with a video camera and light at the end
and placed internally to examine the colon for polyps. If polyps are found, a doctor can do apolypectomy, a procedure that removes polyps from the colonic wall. Doctors can also then test thepolyp for cancerous cells. Colonoscopy is the only test that can be used to both find and remove
polyps. There are, however, other useful screening tests, including imaging and at-home tests thatcan allow patients to examine their stool for small amounts of blood. Occasionally, polyps are toolarge to be removed during a colonoscopy, in which case, the next step is surgery. If blood andTedEd-26

Who's at Risk for Colon Cancer?

imaging tests then reveal that cancerous cells have spread outside the colon, then a special
treatment, like chemotherapy, may also be required to stop the cancer from escalating. We can also
take on certain habits to reduce our likelihood of developing colon cancer in the first place. There's
evidence that maintaining a healthy weight, not smoking, and being physically active can help. But
most importantly, access to healthcare and regular screenings at crucial times in life are the best
ways to prevent colon cancer.