Catching the Cancers Colonoscopies Miss

March 5, 2008— -- Doctors today were taking a hard look at how colonoscopy may change in light of new data which suggests many potential cancers are being missed -- and the research may even impact how colonoscopy is done and how patients perform the distasteful preparation for the procedure.

Coincidentally, the findings came on the same day a group of medical organizations recommended two tests -- virtual colonoscopy and a stool DNA test -- to supplement traditional colonoscopy screening tests for colon cancer.

But ironically, neither of these new additions are adequate for detecting the flat, non-polyp lesions that the new research, published Wednesday in the Journal of the American Medical Association, suggests could pose a huge a risk for colon cancer.

Researchers at the Veterans Affairs Palo Alto Health Care System studied 1,819 patients who underwent a colonoscopy. The study found nearly one in 10 of the patients had nonpolyp lesions, and that these lesions were 10 times as likely to contain cancerous cells as the traditional polyps.

Moreover, these nonpolyp lesions are much harder to find and to remove than regular polyps because they are flat and are often the same color as the healthy tissue surrounding them.

Japanese researchers published studies about these flat lesions in the 1980s and 1990s, but until now, American doctors tended to think that the flat, nonpolyp lesions were signals of a type of colon cancer that is less common in the United States. However, these new findings provide evidence that this type of colon cancer is also prevalent here.

Dr. Douglas Rex, medical director of endoscopy at the Indiana University Hospital, said the findings suggest doctors must become more aware of this type of lesion and be on the lookout for its telltale signs.

"In this study, these lesions were seen using widely available colonoscopes and careful examination," said Rex. "These tools are available to everyone doing colonoscopy — they just need to be used."

Doctors, Patients Must Not Be Hasty

In addition to better using the equipment available for traditional colonoscopies, Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, said the new findings should convince many endoscopists to take a longer time to perform the procedure with utmost attention to detail.

"[This study] will raise awareness and will clearly look at the issue of [how] important [it is] that doctors who do screening colonoscopies take the time to do it right," Lichtenfeld explained.

Current recommendations are that the colonoscopy exam should last at least six minutes. Lichtenfeld believes the amount of time given to the exam should be increased in light of these findings.

"That is a quality issue, and we have to pay attention to that," Lichtenfeld said.

However, Dr. Roy Soetikno, lead study investigator and chief of endoscopy at the VA Palo Alto Health Care System, said he believes his research will not necessarily result in a change of practice for doctors performing these procedures. Rather, he said it will force many doctors to perform colonoscopies more carefully, more slowly, and by the book.

And he added that for patients, the findings could underscore the importance of thorough screening — particularly considering the fact that colon cancer is the third most common cancer for both men and women in the United States, with about 108,070 new cases of colon cancer and 49,960 deaths from the disease each year, according to the American Cancer Society.

"Patients need to know that colorectal cancer is an absolutely preventable disease, and they need to take part in preventing disease by having themselves screened according to recommended age groups," Soetikno said.

Dr. J. Randolph Hecht, director of the UCLA GI-Oncology program said that the new research may also point to the importance of patients following more conscientious prescribed bowel-cleaning regimens before screenings.

Patients are required to "cleanse their colon" before a colonoscopy by taking a high-quality bowel cleanser in a split dose. This means that half of the dose of bowel cleanser must be taken the day before the colonoscopy, and the other half must be taken the day of the procedure.

If the instructions for split-dosing are not carefully followed and the patient chooses to take a full dose of the bowel cleansing solution the day before the procedure, the long interval of time between taking the bowel cleanser and undergoing the colonoscopy can lead to the buildup of chyme, mucous and thick secretions in the entry to the colon — a place where flat lesions are particularly prevalent.

"I think that if subtle lesions are important, then the quality of the prep becomes more important," Hecht said.

A Blow to Virtual Colonoscopy?

Before these findings, many experts believed that the "virtual colonoscopy" — a method of colorectal cancer screening that uses X-rays and computers to produce 2- and 3-D images of the colon — would someday replace the traditional method of colonoscopy.

Now, to the chagrin of patients who hoped the virtual colonoscopy would allow them to avoid the dreaded tube-through-the-rectum technique, experts believe the importance of evaluating these "hidden" lesions will convince many doctors to continue to use traditional colonoscopy methods until the technology of virtual colonoscopies is perfected.

"This is going to be a problem for virtual colonoscopy because they have to have a significant change in shape in order to be able to detect a lesion," said Rex.

"I still feel that our best bet at really high level protection is in [traditional] colonoscopy because it provides single session diagnosis and treatment — it removes polyps that may actually prevent cancer."

Any Test Better Than No Test

Still, virtual colonoscopy made it into the guidelines released Wednesday by the Cancer Society, the American College of Radiology, and the U.S. Multi-Society Task Force on Colorectal Cancer -- a group that comprises representatives from the American College of Gastroenterology, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy.

Lichtenfeld said this new recommendation comes as an effort to offer patients a "menu of options" for cancer screening. The hope of these organizations is that hope those people who are scared off by traditional colonoscopy will choose to have one of these alternative screening methods rather than nothing at all.

"Patients want different things, so it's important for us to offer a range of options so they can decide with their healthcare professional what is best for them," Lichtenfeld explained. "That's just the reality of where we are. No screening test is perfect, and we're losing thousands of patient's lives every year because we've failed to get more people screened.

"We just want to make sure you get something rather than nothing."