Virtual colonoscopy, which uses X-ray imaging to scan for colon cancer, shows promise, but is not ready to replace traditional colonoscopies yet, experts said on Wednesday.

Virtual scans are still not as good as the old-fashioned colonoscopy at spotting smaller pre-cancerous growths and polyps, a task force of experts said.

Colon cancer is the second leading cause of cancer death in the United States, having killed more than 57,000 people last year, according to the American Cancer Society.

Everyone over 50 is advised to undergo screening for the disease, which is easily cured if caught early.

The preferred method is a colonoscopy, which involves inserting a small imaging device through the rectum into the colon. A tiny cutting instrument is attached so the doctor can remove growths on the spot and check them for cancer.

Computed tomography colonoscopy uses X-rays and computer programs that create a fairly clear image of the colon from the outside.

It is less invasive than a colonoscopy, but still requires taking laxatives or using an enema, and fasting to prepare - all of which many people are reluctant to do. And if a lesion is seen, then a traditional colonoscopy is still needed as a follow-up.

Virtual colonoscopy has received much media attention and some doctors have hoped it might appeal to people who refuse to undergo a traditional colonoscopy.

The American Gastroenterological Association put together a task force of gastroenterologists, radiologists and epidemiologists to see how useful the technique might be.

“CT colonography is currently not the most accurate or convenient test, but may in the future be included in the mix of colorectal cancer screening options available to patients and physicians,” Dr. Emmet Keeffe, president of the AGA said.

“While the virtual aspect of the test sounds appealing, it isn’t a panacea,” Keeffe added in a statement.

“Many practical issues still need to be addressed, including standardization of test performance, patient preparation and interpretation of test results before CT colonography can be recommended for routine clinical practice.”

Other approved tests for colon cancer include a barium enema, the fecal occult blood test that checks for blood in the stool, and flexible sigmoidoscopy, which can examine a smaller part of the colon.