Colonoscopy Techniques Compared

Colonoscopy Techniques Compared
Effectiveness in Colorectal Cancer Screening Examined

By Dawn Dorsey

Can people avoid invasive, traditional colon cancer screenings by using a new technique involving virtual colonoscopy, a type of X-ray? The jury is still out on how the two methods compare, but scientists who have recently closed enrollment for a nationwide study hope to find out within the year.

Significance of study

If virtual colonoscopy, or computerized tomographic colonography (CTC), is found to be as effective as traditional colonoscopy, the method would provide an alternative that health professionals hope might increase screenings.

Even though traditional colonoscopies offer tremendous potential to save lives, many people shy away from them because of expense or apprehension about discomfort, says Revathy Iyer, M.D., associate professor in M.D.Andersons Division ofDiagnostic Imaging and principal investigator on the M.D.Anderson study. As the population ages, it is going to be increasingly important to provide testing that is easier to perform and more convenient for the patient.

Early detection of colorectal cancer gives patients a 90% five-year survival rate, according to the American Cancer Society (ACS). However, not enough people are undergoing the screenings, and fewer than four in 10 colorectal cancers are caught early, the ACS says. Once the cancer has spread to distant sites, survival rates drop to as low as 10%.

Research methods

The study, which closed its patient enrollment this month, is being coordinated by the American College of Radiology Imaging Network (ACRIN). It includes more than 2,600 patients at 17 sites nationwide. Participants are at least 50 years old and already were scheduled for screening colonoscopies.

Study participants received colonoscopies and CTCs and were asked to complete questionnaires after the tests.

Researchers hope to learn more about CTC, including:

• Effectiveness of identifying polyps
• CTC techniques among centers
• Types of lesions identified
• Development of a database
• Patient preferences
• Cost-effectiveness

Study description

Virtual colonoscopy uses X-rays and computed tomography (CT) to take two- or three-dimensional images of the large intestine and rectum.

Traditional colonoscopy involves inserting a lighted scope into the colon and rectum to check for areas of abnormality.

Characteristics of virtual colonoscopy:

PreparationLaxatives must be taken to cleanse the bowel the day before.

SedationNo sedation is required.

Side effectsPrior to the procedure, a thin tube to insert air into the colon is placed in the rectum. Some patients feel minor discomfort when air is inserted. Serious side effects are rare.

Side effects from the CT scan itself are minimal, the same as with any X-ray, which involves exposure to a small amount of radiation.

TimeBecause theres no sedation, the CT takes less time than traditional colonoscopy. The actual procedure takes 10-15 minutes.

CostSome insurance providers, including Medicare, do not pay for routine screening using CTC.

If a polyp is found, physicians perform a traditional colonoscopy to obtain a biopsy.

Characteristics of traditional colonoscopy:

PreparationLaxatives must be taken to cleanse the bowel the day before.

SedationPatients require sedation and must arrange for transportation.

Side effectsThough incidence is low, risks might include serious bleeding or colon perforation issues.

TimeThe procedure takes from 15 to 30 minutes, and postoperative recovery requires 45 to 60 minutes. Most patients miss a day of work.

CostNationwide, the median cost for a colonoscopy is $1,000-$1,500. The procedure may be covered by insurance.

Background

Two previous studies on whether CTC and colonoscopy can give comparable results were inconclusive. We are hoping that this will be the tiebreaker that tells us if CTC is accurate enough for widespread screening use, Iyer says.

Whats next?

Now that the study is closed to enrollment, researchers will compile and categorize data. Publication of the final data is expected within the next 10 to 12 months.