By Eduardo Grunvald, M.D.
The subject is something of a secret… not dinner table conversation. But not talking about colon health can be the last secret you ever keep. That’s why public health educational and information campaigns over the last few years has saved lives. March is National Colorectal Cancer Awareness Month, and understanding preventive recommendations help make this cancer the most preventable of all cancers.
National statistics from 2006 show over 140,000 people were diagnosed with colon cancer and over 50,000 people died from the disease. It is the second leading cause of cancer death in United States. Among Hispanics, it is the third leading cause of cancer deaths in this nation, accounting for over 2,300 deaths per year. Unfortunately, Hispanics and other minorities are less likely to be screened for the disease, and compared to their non-Hispanic white counterparts, usually have more advanced disease when diagnosed.
The colon, or large intestine, is the last portion of the digestive tract, where most of the water is reabsorbed from human waste prior to being excreted. The rectum is the portion between the colon and the outside world. Compared to other parts of the digestive system the esophagus, the stomach, the liver, the pancreas, and the small intestine - the colon and rectum are more likely to develop cancer.
As is the case with most cancers, this disease develops very slowly over time, usually over a period of years. It has to start as one cell, long before it can be detected. Gradually, this cell will multiply and eventually turn into a small growth, called a polyp. Some polyps are “pre-cancerous” and some are not. So removing them serves two purposes -analyzing them in the laboratory to know the type and more importantly, preventing their growth into cancer.
How are they taken out? A long and thin flexible instrument with a light and camera on the end is inserted into the colon and snaked through, so the doctor can see the inside of the tortuous organ. If a polyp or strange looking area is seen, instruments can be wired through the tube to either take a biopsy, a snippet of tissue, or remove any polyps. The two types of procedures used are the colonoscopy or flexible sigmoidoscopy. Colonoscopy is performed with a longer tube that can visualize the entire colon. The sigmoidoscopy uses a shorter tube, allowing only a third of the colon to be seen.
Although the procedure sounds very uncomfortable, colonoscopies are usually performed with sedation, and most people say the worst part is drinking the cleansing preparation the night prior. The website www.preventcancer.org/colorectal has a link to an excellent animated video of a colonoscopy.
Current recommendations call for either a colonoscopy every 10 years, or a sigmoidoscopy every five years along with yearly tests for microscopic blood in the stool, called fecal occult blood testing. There is also a procedure called a barium enema, where special x-rays are taken to visualize the lining of the colon. Although there are several combinations of procedures that are acceptable for screening, depending on resources, a complete colonos-copy has generally become the screening procedure of choice.
There is also a procedure called a CT colonography, or more commonly known as a virtual colonoscopy, whereby the colon is inflated with air prior to performing a CAT scan. The main advantage of this procedure is that it is not invasive, but very small polyps may be missed. It is a relatively new technology, and is currently under investigation to assess the efficacy compared to conventional colonoscopy, which is the gold standard. As of this time it is not endorsed as a primary screening procedure under current preventive guidelines.
Most people should start screening at age 50. However, there are certain people with strong family histories of colon cancer or with other digestive diseases who may have increased risk of developing colorectal cancer, and should start screening at an earlier age or with more frequency. Talk to your doctor for precise recommendations.
As you can see, colonos-copies have made colorectal cancer a preventable disease. There is literally and figuratively light at the end of the tunnel.
For more information on screening for colorectal cancer, in English and Spanish, visit www.cancer.org.
Dr. Grunvald is Associate Clinical Professor, Department of Medicine at the Perlman Internal Medicine Group, UCSD Medical Center.