Colonoscopy Remains the Gold Standard to Detect Colon Cancer

Mar. 11, 2009 — Medical experts say you can still trust a colonoscopy to detect and prevent colon cancer in its earliest stages, even though recent research has pointed out some potential drawbacks in having this procedure.

"Colonoscopy is a good tool," says Dr. Durado Brooks, national director of prostate and colorectal cancers for the American Cancer Society (ACS). "In the right hands, it is an effective tool. But we have known for a long time it is not a perfect tool."

In December, 2008,Canadian researchers reported that colonoscopies were good at discovering early signs of cancer on the left side of the colon, or large intestine, but were not as good at finding cancer or polyps on the right side, deeper inside the colon's pathway.

While doctors are carefully consideringthe study conclusions, they continue to support colonoscopies asa vital weapon in the fight against colon cancer. This isa key point to remember during March, which is National Colorectal Cancer Awareness Month.

Importance of Colon Cancer Screening
ACSsays colorectal cancer is the third most common cancer found in men and women in the US. Almost 108,070 new cases of colon cancer will be diagnosed this year; combined will rectal cancer, these conditions will attribute to approximately 50,000 deaths.

In recent years, the incidence rate of colon cancer has decreased by 2.3 percent annually, according to theUS Centers for Disease Control and Prevention (CDC). Thedeath rate also has continued to decrease, dropping 4.7 percent yearly.

Decreases indeaths and incidence rates have largely been attributed to the use ofa colonoscopy as a screening tool. Whencolon cancer is diagnosedearly and treatment begins immediately,patients enjoy a five-year relative survival rate of 90 percent.

More importantly,screening for colon cancer plays a vital role in the prevention of colon cancer; it provides doctors with an opportunityto locate and remove pre-cancerous polyps.

"We know the incident rate has been falling for close to a decade now, and that coincides with the increase in screening," Dr. Brooks says.

Canadian Research Study on the Use ofColonoscopy as a Screening Tool
Results of the 2008 Canadian research study appeared to focus onthe importanceto ensurethat doctors received thorough training in performing colonoscopies, says Dr. Bernard Levin, professor of gastrointestinal medicine and nutrition and vice president of cancer prevention at the University of Texas M.D. Anderson Cancer Center in Houston.

According to Dr. Levin, only 30 percent of the colonoscopies were performed by gastroenterologists who werespecifically trained to perform the procedure. The remaining colonoscopies were done by general surgeons or technicians who may or may not had received previous andadequate training in this field, he adds.

"It is not just a question of sticking a tube into the colon and looking around - it's not that simple. You have to have some training, and that training has to be specific," Dr. Levin says.

Dr. Brooks adds that the study has its drawbacks, because it looked at people who had received a colonoscopy at some earlier point, and died of colon cancer. "It may be there was no evidence of cancer at the time of the examination, and then cancer developed later," he says.

There is also no evidence onhow well-prepared the patients were for their colonoscopy, Dr. Levin says. If their colons were not thoroughly cleaned out ahead of time, cancers and polyps could have been missed. Drs. Levin and Brooksagreed that the Canadian study probably overstated the problem.

"Colonoscopy is not 100 percent accurate even in the best of hands, but it's probably better than the Canadian study gives it credit for," Dr.Levin says.

Is There a New ScreeningTool for Colon Cancer?
While colonoscopy continues to remain the best method to detect colon cancer, recent studies have shown that othermethods appear to be promising.

For instance, a researchstudy found that virtual colonoscopy - in which the colon is examined through CT scans - was effective in discovering 90 percent of precancerous lesions larger than 10 millimeters. According to Dr. Levin this procedure could be a good screening tool, especially for people with average risk of colon cancer.

"Five millimeters and below, it is likely virtual colonoscopy is not as accurate, but so what?" Dr. Levin says. "If you miss seeing one of those, it's likely its growth with not be significant, and it does not pose a significant cancer risk. You would pick it up the next time you undergo this procedure."

Always consult your physician for more information.