March is colon cancer awareness month! Colorectal cancer is the third most common cancer in the United States and the second leading cause of death from cancer. Colorectal cancer affects people in all racial and ethnic groups and is most often found in people age 50 and older. If everyone age 50 and older were screened regularly, 6 out of 10 deaths from colorectal cancer could be prevented. Communities, health professionals, and families can work together to encourage people to get screened.
Colon cancer and cancer of the rectum can begin as a small polyp, detectable through regular cancer screening, such as colonoscopy. Colon cancer symptoms include a change in bowel habits or bleeding, but often there are no symptoms. With early detection, surgery, radiation, and/or chemotherapy can be effective treatment. Cancer starts when cells in the body start to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. Most colorectal cancers start as a growth on the inner lining of the colon or rectum.
If cancer forms in a polyp, it can grow into the wall of the colon or rectum over time. The wall of the colon and rectum is made up of many layers. Colorectal cancer starts in the innermost layer (the mucosa) and can grow outward through some or all of the other layers. When cancer cells are in the wall, they can then grow into blood vessels or lymph vessels (tiny channels that carry away waste and fluid). From there, they can travel to nearby lymph nodes or to distant parts of the body. The stage (extent of spread) of a colorectal cancer depends on how deeply it grows into the wall and if it has spread outside the colon or rectum.
When a colorectal cancer is diagnosed, additional tests are performed to determine the extent of the disease. This process is called staging. Staging determines how advanced a colorectal cancer has become. The staging for colorectal cancer ranges from stage I, the least advanced cancer, to stage IV, the most advanced cancer. Surgery is the most common initial medical treatment for colorectal cancer. During surgery, the tumor, a small margin of the surrounding healthy intestine, and adjacent lymph nodes are removed. The surgeon then reconnects the healthy sections of the bowel. In patients with rectal cancer, the rectum sometimes is permanently removed if the cancer arises too low in the rectum.
Follow-up exams are important for people with colorectal cancer. The cancer can come back near the original site, although this is unusual. If the cancer returns, it typically does so in a distant location such as the lymph nodes, liver, or lungs. Individuals diagnosed with colorectal cancer remain at risk of their cancer returning for up to 10 years after their original diagnosis and treatment, although the risk of recurrence is much higher in the first few years. The American Cancer Society suggest colonoscopy, for early detection of colon cancer, as it is the most accurate method. It visualizes the entire colon and allows the surgeon to remove polyps during the procedure.