New Choice for Colonoscopy on Horizon

< Apr. 25, 2007 > -- A cutting-edge technology called "virtual colonoscopy" promises fewer complications and better cost-effectiveness than traditional colonoscopy, researchers report in the journal Cancer.

These technologies have been compared before, but the current analysis relies on the notion that identifying and removing polyps smaller than 6 millimeters (almost one quarter inch) won't do much to reduce colorectal cancer cases.

The new technique will not replace traditional colonoscopy.

Easier Options May Lead to More Screening

"Because there's virtually no risk associated with having such small polyps, 90 percent of folks don't need an invasive and expensive colonoscopy to screen for colon cancer," explains lead researcher Dr. Perry J. Pickhardt, an associate professor in the school of medicine and public health and radiologist at the University of Wisconsin in Madison.

"So, here it was easy to show that virtual colonoscopy is a very effective way to filter out these people and hone in on those who really need the more invasive procedure," he says.

Dr. Pickhardt is not suggesting that virtual colonoscopies replace traditional optical screening. But non-invasive screening might up the number of people who decide to undergo screening, he says.

"We need to encourage more folks to get screened, period," says Dr. Pickhardt. "We're not trying to take away from the screening already in place. It's a personal choice. Some people prefer the colonoscopy route compared to virtual colonoscopy, and that's fine. Just so long as you do one or the other."

The disease is highly treatable if caught early, however.

Virtually Painless Exam

Virtual colonoscopy involves a combination of sophisticated X-rays and computed tomography (CT) scans of the abdomen after it has been pumped with air. A two- and three-dimensional computer model of the gastrointestinal tract is then generated, potentially revealing cancerous and precancerous lesions. If dangerous lesions are spotted, a second, more invasive procedure is required.

Unlike traditional colonoscopy, the virtual method is faster, involves no sedation, no post-procedure recovery, and no risk of invasive complications such as abdominal bleeding or life-threatening bowel perforation.

However, the American Cancer Society ( ACS) has not yet backed this option as a proven screening method, citing the need for further research.

Instead, the group suggests other screening methods, including blood stool tests; a barium enema combined with X-rays; a flexible sigmoidoscopy (involving the insertion of a two-foot-long optical tube through the rectum to examine the lower colon); and traditional optical colonoscopy, which involves the insertion of a longer lighted tube to examine the entire colon.

All people over age 50 are encouraged to undergo a regular colonoscopy once every 10 years, or either a barium enema or a flexible sigmoidoscopy (with or without a yearly blood test) once every five years.

New Study Details

To compare some of these options, Dr. Pickhardt and his colleagues developed a mathematical model involving 100,000 patients with an average risk for colorectal cancer. They noted that 75 percent of the American population is subject to such risk.

Polyp searches were based on one of two thresholds: those measuring 6 millimeters in diameter and up, and lesions of any size.

The model indicated that 2,940 patients would ultimately go on to develop colorectal cancer.

The simulation also revealed that flexible sigmoidoscopy screenings reduced the rate of cancer by just over 31 percent, while traditional colonoscopy reduced the rate by just over 40 percent.

Virtual colonoscopies were only slightly less efficient than the traditional method -- achieving an almost 38 percent reduction when polyps of all sizes were considered. The prevention rate dropped slightly, to 36.5 percent, when screenings focused only on polyps 6 millimeters and up.

Virtual colonoscopy also had the added benefit of dramatically reducing the need for unnecessary polyp removal. Nearly 78 percent fewer patients went on to have an invasive polyp removal after a virtual screening compared with patients who underwent a regular colonoscopy.

And when virtual screenings focused solely on lesions 6 millimeters and up nearly 12,900 additional unwarranted polyp removals were avoided.

However, Dr. Pickhardt noted that the high-tech procedure is not yet widely available.

"It's definitely ready for primetime, but people don't have it everywhere yet," he says. "The technology is getting better and better, and I can tell you that it will continue to improve. But most radiology practices aren't going to invest in the necessary software, because insurances aren't generally paying for it yet."

The ACS's director of cancer screening, Robert Smith, said his organization is taking a wait-and-see approach toward virtual colonoscopy. However, he believes the technology holds great promise.

Always consult your physician for more information.

About Colorectal Cancer

When malignant cells are found in the colon or rectum the diagnosis is colorectal cancer, a curable condition.

The colon and the rectum are part of the large intestine and digestive system. Because colon cancer and rectal cancers have many features in common, they are sometimes referred to together as colorectal cancer. Cancerous tumors found in the colon or rectum also may spread to other parts of the body.

Excluding skin cancers, colorectal cancer is the third most common cancer in both men and women. It is estimated by the American Cancer Society that 153,760 colorectal cancer cases are expected in 2007. The number of deaths due to colorectal cancer has decreased, which is attributed to increased screening and polyp removal.

The following are the most common symptoms of colorectal cancer. However, each individual may experience symptoms differently.

People who have any of the following symptoms should check with their physicians, especially if they are over 50 years old or have a personal or family history of the disease:

• a change in bowel habits such as diarrhea, constipation, or narrowing of the stool that lasts for more than a few days

• rectal bleeding or blood in the stool

• cramping or gnawing stomach pain

• decreased appetite
  vomiting

• weakness and fatigue

• jaundice - yellowing of the skin and eyes

The symptoms of colorectal cancer may resemble other conditions, such as infections, hemorrhoids, and inflammatory bowel disease. It is also possible to have colon cancer and not have any symptoms.

Although the exact cause of colorectal cancer is not known, it is possible to prevent many colon cancers with the following:

• diet and exercise - It is important to manage the risk factors you can control, such as diet and exercise. Eating more fruits, vegetables, and whole grain foods, and avoiding high-fat, low-fiber foods, plus appropriate exercise, even small amounts on a regular basis, can be helpful.

• drug therapy - Some studies have shown that low doses of nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, and estrogen replacement therapy for post-menopausal women may reduce the risk of colorectal cancer. Discuss this with your physician.

• screenings - Perhaps most important to the prevention of colorectal cancer is having screening tests at appropriate ages. Because some colorectal cancers cannot be prevented, finding them early is the best way to improve the chance of successful treatment, and reduce the number of deaths caused by colorectal cancer.

Always consult your physician for more information.