Virtual Colonoscopy Finds Colorectal Cancer

New CT scans using 3-D images accurately detect disease, researchers report

MONDAY, Dec. 1, 2003 (HealthDayNews) -- New technology that uses 3-D images may soon make virtual colonoscopy a reliable screening tool.

"We have proved that virtual colonoscopy is a viable screening option," says lead researcher Dr. Perry J. Pickhardt, an associate professor of radiology at the University of Wisconsin Medical School.

This technique compares favorably to the current "gold standard" of conventional colonoscopy, he adds. Pickhardt and his colleagues report their findings in the Dec. 4 issue of the New England Journal of Medicine.

A conventional colonoscopy is the visual exam of the upper parts of the lower intestine using a flexible instrument about 3 feet long that is inserted through the anus into the colon. Patients are sedated during the procedure. The virtual colonoscopy, however, is completely noninvasive.

In their study, Pickhardt's team had 1,233 asymptomatic men and women undergo virtual and conventional colonoscopies. All the patients were considered at low risk for the disease.

To the surprise of Pickhardt's group, both methods were equally accurate. However, one of two malignant polyps detected in this experiment was missed by the conventional colonoscopy.

"Our 3-D approach really set us apart from other studies and is most likely the reason that previous studies using non-3-D CT to detect colorectal cancer were so disappointing," Pickhardt says.

In addition, using state-of-the-art CT equipment and the way the patients were prepped added to the accuracy of virtual colonoscopy, he says.

Those most likely to benefit from virtual colonoscopy are patients with the lowest risk of colorectal cancer, namely those more than 50 years old with no family history of colorectal cancer.

Patients with a higher risk should have a conventional colonoscopy, the researchers say. If a polyp is found by a virtual colonoscopy, the patient would have to undergo a conventional colonoscopy to have the polyp removed, Pickhardt notes.

Based on these results, "virtual colonoscopy should join conventional colonoscopy as a major component of colorectal cancer screening," he says.

Pickhardt hopes this new screening technique will encourage more people to get screened. He points out that while colorectal cancer is the second leading cause of cancer deaths in the United States, it is largely preventable with routine screening. "We know that screening will save lives," Pickhardt says.

Dr. J. Thomas LaMont, a professor of medicine at Harvard Medical School and co-author of an accompanying editorial, says "the importance of this study is that it offers patients another screening method instead of colonoscopy."

LaMont believes this new screening technique will encourage more people to get screened. The main stumbling block to using virtual colonoscopy now is that it is not covered by insurance, he notes.

Right now only half of Americans are screened for colorectal cancer, LaMont says: "We should do a lot better, because this is a disease that, if found early, is completely curable."

And there's more new information about colorectal cancer. Smoking significantly increases the risk of death from the disease, claims a new study in the Dec. 1 online issue of Cancer.

"We found a higher risk of death from colorectal cancer among men and women who smoked at least a pack of cigarettes a day or more," says lead author Dr. Susan M. Gapstur, an associate professor and epidemiologist at Northwestern University's Feinberg School of Medicine.

"This association appeared to be much stronger among younger women compared with men," she adds.

Gapstur and her colleagues collected data on 32,299 men and women from the Chicago Heart Association Detection Project in Industry study, which followed subjects for an average of 26 years.

The researchers found women who smoked one to 20 cigarettes a day had a two times greater risk of dying from colorectal cancer than women who never smoked.

In addition, women who smoked more than 20 cigarettes a day had an almost three times greater risk of dying from colorectal cancer compared with nonsmokers. However, there appeared not to be an increased risk for men and women over 50 when the study began.

"Quitting smoking or not starting smoking could potentially lead to reduced rates of colorectal cancer," Gapstur says.

This finding adds to the body of literature that says smoking is really bad for your health, she says. "It's not just lung cancer, it's not just heart disease, but also colorectal cancer, which is a major cause of morbidity and mortality in the U.S."

In an accompanying editorial, Dr. Graham Colditz and Kathleen Yaus of the Harvard School of Public Health, say this study, along with other evidence, should provide further impetus "for even greater emphasis on prevention of adolescent smoking."

More information

To learn more about colorectal cancer, visit the National Cancer Institute or the American Cancer Society.

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