Prevention and early detection are key factors in controlling and curing colorectal cancer. Indeed, colorectal cancer is the second most preventable cancer, after lung cancer. When the cancer is found early, initial treatment can often lead to an excellent outcome. Colorectal cancer is cancer that occurs in the large intestine and rectum. The colon is a muscular tube that is about five feet long. It absorbs water and nutrients from food. The rectum, the lower six inches of the digestive tract, serves as a holding place for stool, which then passes out of the body through the anus. This year, about 148,000 people in the United States will be diagnosed with colorectal cancer. Although many people think of colorectal cancer as a disease that primarily affects men, it is slightly more common in women. Today, the average person has about a 1 in 20 chance of developing colorectal cancer during his or her life.
The colon is divided into four sections: the ascending colon, transverse colon, descending colon, and sigmoid colon. Most colorectal cancers arise in the sigmoid colon -- the portion just above the rectum. They usually start in the innermost layer and can grow through some or all of the several tissue layers that make up the colon and rectum. The extent to which a cancer penetrates the various tissue layers determines the stage of the disease. Most colorectal cancers grow slowly over a period of several years, often beginning as small benign growths called polyps. Removing these polyps early, before they become malignant, is an effective means of preventing colorectal cancer.
Colorectal cancer sometimes arises without any symptoms. For this reason, screening tests (such as colonoscopy and a test for blood in the stool) are recommended to detect the cancer early, when it is more curable.
When symptoms do occur, however, they may include the following:
Some of these symptoms may be caused by other conditions. But you should see your doctor if they persist. Any incidence of rectal bleeding or blood in the stool should be brought to your doctor's attention.
The best way to cure colorectal cancer is to prevent it from occurring in the first place. A regular program of screening examinations is the best way to ensure an early diagnosis, and an early diagnosis offers the best chance for a cure.
Screening & Diagnostic Tests
Colorectal cancer screening and diagnosis may involve one or more of a number of procedures:
Virtual colonoscopy is a new technique that uses CT scans to create a 3-D image that can be used to evaluate the bowel. At this time, it is still a research tool and is not generally available. It is also important to note that, while this is a promising technique, it does not allow for a biopsy or polyp removal at the same time an abnormality is found.
For more information about diagnostic tests, see Staging.
If you do not have an increased risk of colorectal cancer because of your personal or family medical history, we recommend the following screening tests, beginning at age 50:
If you have an increased risk of colorectal cancer because of your personal or family medical history, you should have a colonoscopy every 5 years beginning at age 40, or younger if hereditary non-polyposis colorectal cancer (HNPCC) is suspected. For first-degree, direct relatives of patients with colorectal cancer that has presented before age 50, screening should begin 10 to 20 years before the age of the diagnosed patient. For example, if your father is diagnosed with colorectal cancer at age 48, then you should begin your own colorectal cancer screening between ages 28 and 38.
If tests show that you have colorectal cancer, additional examinations may be performed to determine its extent -- a process called staging. Knowing how far your cancer has progressed is important when deciding what regimen of treatment might be most appropriate for you. The following tests are routinely used to stage colorectal cancer:
Depending on your specific clinical situation, these additional tests may be ordered:
The choice of treatment for colorectal cancer depends on the stage of the disease -- that is, how large the tumor has grown, how deeply it has invaded the layers of the colon or rectum, and whether it has spread to other organs (most commonly the liver), lymph nodes, or other parts of the body.
Treatment options include surgery, radiation therapy, chemotherapy, and combinations of these approaches.