The US Food and Drug Administration has approved the first oral treatment for colorectal cancer that has spread to other parts of the body.
The drug is called Xeloda (capecitabine), and reacts with an enzyme in the body that converts the drug into 5-fluororurocil, or 5-FU, a therapy standard in the treatment of colorectal cancer. The treatments are less disruptive, as patients can take their two daily doses at home, whereas standard chemotherapy treatment is delivered intravenously at an outpatient center.
Colon cancer, the most common type of colorectal cancer, is the third most common cancer in the US. For approximately 20 percent of its victims, the cancer has already spread by the time of diagnosis. 50 percent of all patients with colorectal cancer will develop a metastasis, and die from the disease.
But perhaps the darkest statistic about colon cancer is this: fewer than one third of the people who should be screened for colon cancer ever get the simple tests that can identify the cancer in its early, curable stages.
Taking the plunge
It often takes a great deal of discussion to get people to feel comfortable with what can be perceived as embarrassing or uncomfortable tests. Now and then patients will say things like, "I'm better off not knowing," or, "Why go looking for trouble?"
What these patients do not realize is that colon cancer is one of the deadliest diseases in our country today, but if caught early, it is 90 percent curable.
The following are brief descriptions of some of the most common screening techniques we use today.
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Digital rectal exam
The digital rectal exam looks for colon cancer in two ways. First, it involves the insertion of a lubricated, gloved finger into the rectum. A full 10 to 15 percent of tumors can be identified this way. Second, testing the stool for traces of blood at the time of the exam identifies people who should have additional testing to rule out a colon cancer.
Fecal occult blood testing
The most common screening test for colon cancer is the fecal occult blood test, or FOBT. It's easy to do, relatively inexpensive, and can be done at home by collecting small samples of stool on a test card. These samples are tested in a laboratory or at a doctor's office for traces of blood in the stool. For those people who show traces of blood, a colonoscopy is recommended, so that doctors can look for polyps or potentially cancerous tumors.
Several very large clinical studies have compared groups of healthy people over the age of fifty who used FOBT (with follow-up colonoscopy for positive tests) for colon cancer screening, to groups who received no screening. Over time, mortality from colon cancer in the screened groups was lower by a full third.
Barium enema
Barium enema uses x-rays to look for tumors or polyps in the lining of the colon. With multiple x-ray images, radiologists are able to get pictures of the entire length of the colon. If a tumor or polyp is identified on a barium enema, further testing with a colonoscopy is usually recommended.
Sigmoidoscopy
Rigid sigmoidoscopy involves the insertion of a thin, rigid tube fitted with a light and lenses into the rectum, to visualize the lining of the last 25 cm of the colon. This procedure has been replaced, to a large extent, by flexible sigmoidoscopy, which uses fiberoptic technology to allow for a thinner, flexible tube that can reach up to 60 cm into the colon.
Although somewhat uncomfortable, this procedure has very few risks, and can usually be done in an office or clinic. Given that as many as 80 percent of colon cancers arise in the parts of the colon that can be reached and visualized with the sigmoidoscope, it can be used to find the majority of tumors or small polyps that might harbor cancerous cells. It can also be used to remove small lesions, or biopsy large ones.
Colonoscopy
The colonoscope can reach all the way to the end of the colon. Theoretically, colonoscopy can allow a doctor to see and find 100 percent of polyps and potential cancers, although lesions can be missed if they are very small or obscured by stool.
Through the colonoscope, a doctor can inspect the lining of the colon, biopsy suspicious lesions, and even remove whole polyps. In some cases where very early colon cancers rest completely within the substance of a polyp, removal of the polyp through the scope can completely cure the patient, with no need for further treatment for the cancer.
Colonoscopy carries with it, however, a small risk of complications, including bleeding and perforation of the colon. The procedure usually requires sedation and often must be done in specially equipped hospital centers or clinics. It is also expensive, compared to the other screening tests for colon cancer.
As colonoscopy is the most thorough diagnostic tool for colon cancer, there are several large trials underway investigating ways in which this test might be incorporated into an effective and tolerable screening program.
American Cancer Society colorectal cancer screening guidelines:
Beginning at age 50, both men and women should follow one of the five screening options below:
Yearly fecal occult blood test (FOBT) Flexible sigmoidoscopy every 5 years Yearly fecal occult blood test plus flexible sigmoidoscopy every 5 years* Double contrast barium enema every 5 years Colonoscopy every 10 years
*Of the five options above, the American Cancer Society prefers yearly FOBT combined with flexible sigmoidoscopy every 5 years.
Talk with your health care provider and become informed about the issues related to screening for colon cancer.
