An X-ray technique called virtual colonoscopy appears to be as effective as the conventional procedure for detecting polyps in the colon but is less invasive, does not require sedation and eliminates the risk of inadvertently puncturing the intestine, researchers said yesterday.
The new procedure does not eliminate the onerous 24-hour cleansing procedure in which wastes are washed out of the intestines - a process that many patients find the most objectionable part of the procedure.
And a regular colonoscopy is required if polyps are detected.
Nonetheless, the virtual procedure minimizes the tremendous psychological barrier that prevents a majority of Americans from undergoing screening for colorectal cancer - fear of having the long metal endoscope bearing a tiny TV camera inserted through their rectum and snaked through their intestines.
Colon cancer strikes an estimated 105,500 Americans each year and kills 57,000, making it the second leading killer after lung cancer. But the disease is highly curable if detected early by colonoscopy, and the vast majority of those deaths could be avoided.
Currently, however, only 37 percent of tumors are detected early enough to treat.
"Virtual colonoscopy is an accurate screening tool ... and this hopefully will lead to more widespread screening," said Dr. Perry J. Pickhardt of the University of Wisconsin Medical School. "If we can screen more patients, we know it will prevent cancers and save lives."
Pickhardt presented his findings yesterday at a Chicago meeting of the Radiological Society of North America.
They will be published later this week in the New England Journal of Medicine.
In an editorial in the journal, Dr. Thomas Lamont of the Beth Israel Deaconess Medical Center in Boston suggested that the technique is now "ready for prime time."
Virtual colonoscopy uses a high-tech CT scanner to produce images of the intestines, enabling researchers to identify polyps, which are frequently precursors of tumors.
Smaller studies in the past have produced mixed results about its efficacy. Occasionally, for example, the technique would show small traces of fecal matter that would be misidentified as polyps.
Pickhardt and his colleagues refined the technique, using new software that produced a three-dimensional image rather than the two-dimensional one achieved in previous studies.
The team studied 1,233 adults at four medical centers, subjecting patients to both a conventional colonoscopy and a virtual one.
Overall, they found that the virtual technique detected about 92 percent of polyps large enough to be a potential problem, while conventional colonoscopy detected about 89 percent.
The team found two malignant polyps; the virtual technique identified both, while the conventional procedure missed one.
Surprisingly, 54 percent of the patients found the virtual colonoscopy to be more uncomfortable, probably because air is pumped into the intestines to inflate them slightly, allowing better viewing. Air is also pumped in during a conventional procedure, but patients are sedated, so they don't feel it.
But sedation carries its own problems.
Patients are not allowed to drive afterward, so someone must take them to the diagnostic center, and they generally require at least a couple of hours for recovery.
With virtual colonoscopy, "There's no recovery time," Pickhardt said. "Patients can basically go back to work right after they have the virtual colonoscopy."
Further studies are necessary to confirm Pickhardt's results, especially to show that similar accuracy can be obtained by radiologists working in community hospitals.
Pending those studies, the American Cancer Society will continue to recommend conventional colonoscopy, said the society's Dr. Herman Kattlove.
Insurance also remains an issue.
The virtual colonoscopy costs $600 to $1,000, Pickhardt said, compared with about $650 for the conventional procedure. Currently, Medicare and most insurance companies do not cover the newer procedure, but that could change as further studies are completed.
Meanwhile, less uncomfortable procedures are on the horizon.
Later this week, researchers are expected to reveal favorable results with a miniature television camera and transmitter that is swallowed like a pill.
The camera takes pictures as it passes through the intestines, broadcasting them to a receiver worn on the belt.
This procedure also requires the purging of wastes, but it causes less discomfort because the intestine does not need to be inflated.
The Los Angeles Times is a Tribune Publishing newspaper.