High-Definition Chromocolonoscopy Detects Flat Lesions Better Than HD White-Light Colonoscopy

Deborah Brauser

November 02, 2009

November 2, 2009 (San Diego, California) — Compared with high-definition (HD) white-light colonoscopy, HD chromocolonoscopy does not increase overall detection of adenomas, although it can better detect flat and small lesions, according to a new prospective study funded by the American College of Gastroenterology (ACG) and presented at the ACG 2009 Annual Scientific Meeting.

"Nonpolypoid colon neoplasms are an increasingly recognized precursor for colorectal cancer," said lead investigator Charles J. Kahi, MD, MSc, assistant professor of medicine in the Division of Gastroenterology and Hepatology at Indiana University in Indianapolis, and member of the ACG research committee, during his presentation.

After his presentation, he told Medscape Gastroenterology that "there has been increased attention in the press lately about flat lesions. We know from previous studies that they are prevalent. . . [not just] in Asia, but [also] in the West. So the question [we asked] was: Do we need to be doing something to increase their detection, and overall neoplasm detection? That's where the idea for this study came from."

Dr. Kahi and his team enrolled 660 average-risk patients from 4 American medical centers and randomized them to receive either the HD white-light colonoscopy (n = 389) or the same procedure plus a pan-colonic spraying with indigo carmine dye administered by a spraying catheter through the colonoscope accessory channel (known as HD chromocolonoscopy; n = 321).

"We chose to look at the HD technology because we believe eventually that's going to replace standard definition and we wanted to make this study applicable and valid for years to come," explained Dr. Kahi.

The primary outcomes were patients with at least 1 adenoma and the number of adenomas per patients; patients with flat or depressed lesions were secondary.

Chromo Detects More Flat and Small Adenomas

The overall mean number of adenomas found by the investigators per patient by the end of the study was 1.2 ± 2.1. The mean numbers of flat polyps and flat adenomas per patient were 1.4 ± 1.9 and 0.5 ± 1.0, respectively.

Although there were increases for the chromocolonoscopy group, the differences were not significant in the number of patients with at least 1 adenoma (55.5% vs 48.4%; = .07), the number of adenomas per patient (1.3 ± 2.4 vs 1.1 ± 1.8; = .08), the number of advanced adenomas per patient (0.06 ± 0.37 vs 0.04 ± 0.25; = .3), and the number of advanced adenomas that were less than 10 mm per patient (0.02 ± 0.26 vs 0.01 ± 0.14; P = .4).

However, with chromocolonoscopy, researchers did detect significantly more flat adenomas per patient (0.6 ± 1.2 vs 0.4 ± 0.9; = .01), more adenomas less than 5 mm (0.8 ± 1.3 vs 0.7 ± 1.1; P = .03), and more nonneoplastic lesions (1.8 ± 2.3 vs 1.0 ± 1.3; < .0001).

Finally, only 1 invasive cancer was found in each group (neither was a flat lesion.)

"Our findings do not support the routine use of [HD] chromocolonoscopy for colorectal cancer screening in average-risk patients," said Dr. Kahi at the end of his presentation.

He added: "The high adenoma detection rates observed may be due to the HD technology that we used. A direct comparison of, especially, the flat lesion detection rates with HD colonoscopy, compared with standard-definition colonoscopy, regardless of the chromo, now appears warranted."

After the presentation, Dr. Kahi told Medscape Gastroenterology that the chromocolonoscopy added an average of about 10 minutes to each procedure because of the time spent preparing the dye spray, etc. "So although the adenoma detection results were comparable, the added cost of time was much more."

"I would tell clinicians that they need to see what works best for their practice and decide for themselves if these differences make doing the procedure worthwhile," he concluded.

No Use in the Screening Population

Calling the study "well done and necessary," Dan DeMarco, MD, medical director of endoscopy at Baylor University Medical Center in Dallas, Texas, said that chromocolonoscopy does have a use. "And I use it often. But I don't think it has use in the screening population, which is what the study demonstrated." Dr. DeMarco was not involved with this study.

"We want studies that will show us how to find more polyps with more pathology quicker," explained Dr. DeMarco. "This study showed that they didn't find more pathology and it took a lot longer. Nine or 10 extra minutes on 1 patient is one thing. But if you're going to use it on a screening population, it means you'd use it on sequential patients and, before you know it, that adds up to some significant time."

When asked about the increase in flat lesion detection, he replied: "That's almost like the elephant in the room or something that's looming in the background. Ten years ago we thought that the flat lesions were isolated to the Far East. Then, 2 or 3 years ago, we realized that we have those here too. My take-home from the study is that if you think that you're dealing with flat lesions, you should spray [them]. But to spray everybody doesn't make a lot of sense and is impractical."

This study was funded by the ACG. Dr. Kahi and Dr. DeMarco have disclosed no relevant financial relationships.

American College of Gastroenterology (ACG) 2009 Annual Scientific Meeting: Abstract 12. Presented October 26, 2009.


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