The FDA is seeking input on safety controls and training to improve CT scanners. (Jonathan Hayward/Canadian Press)

A former U.S. Food and Drug Administration scientist says his job was eliminated after he raised concerns about the risks of radiation exposure from CT scanning.

Dr. Julian Nicholas said at a public hearing Tuesday that he and other FDA staffers "were pressured to change their scientific opinion," after they opposed approval to market a CT scanner for routine colon cancer screening. Nicholas said he objected to exposing otherwise healthy patients to the cancer risks of radiation.

After FDA officials pushed ahead with plans to approve the device for cancer screening, Nicholas, now a physician at the Scripps Clinic in San Diego, said he and eight other staffers raised their concerns with the division's top director Dr. Jeffrey Shuren last September. The FDA's review of the device is continuing.

"Scientific and regulatory review process for medical devices was being distorted by managers who were not following the laws," Nicholas said. A month later Nicholas' position was terminated, he said.

Nicholas does not think there was undue influence by the manufacturer in his ouster, but that his more cautious stance was in opposition to that of FDA higher-ups.

The allegations about suppression of scientific dissent come at an inopportune time for the agency.

The FDA announced an effort to improve scanning safety in February after three California hospitals reported hundreds of acute radiation overdoses last year, with many patients reporting lost hair and skin redness.

Science for public safety

Tuesday and Wednesday's meeting was designed to kick off that campaign. The agency is seeking input from physicians and manufacturers on additional safety controls and training to improve CT scanners and other medical imaging devices.

Hundreds of studies have linked certain types of radiation, including the type used in medical imaging, to cancer that can surface decades later.

FDA medical reviewer Dr. Robert Smith, a colleague of Nicholas who also presented at the public meeting, said he hoped the FDA would learn a lesson from Nicholas' testimony.

"Science must not be ignored, suppressed or distorted as that endangers the public," Smith told the audience.

Smith, who still works for the agency, supported Nicholas's conclusion that CT scanning for colon cancer should be rejected on safety grounds.

Agency spokesman Dick Thompson said in a statement the FDA's inspector general looked into allegations of retaliation against agency scientists and did not pursue further action or investigation. The agency's policies do not allow staffers to be penalized for expressing scientific views, he added.

"It is not uncommon for scientists, both internal and external to the agency, to disagree on the safety and effectiveness of products under review or on the steps needed to achieve public health goals," said the FDA statement.

Nicholas said, however, he has never been contacted and is still waiting to hear from the FDA's inspector. He stresses that the inspector's jurisdiction is criminal investigations, not allegations of improper conduct.

Virtual colonoscopy concerns

As a reviewer of medical device applications, Nicholas repeatedly rejected a manufacturers' request to market a CT scanner specifically for colon cancer screening. According to Nicholas, between 1.5 and two per cent of cancers are caused by CT scanning, and he did not want to see scanning used when a conventional colonoscopy could be used instead.

CT scans provide detailed, three-dimensional images of the body, but at a cost: one CT chest scan carries as much radiation as nearly 400 chest X-rays, according to the FDA.

Nicholas said FDA rules legally barred him from naming the manufacturer or discussing the details of its application.

In a June 2009 letter to senior managers, Nicholas stressed that patients should be warned of the radiation risks of CT scanning.

"I hope you understand that the failure to include a warning on the label will mean that patients will undoubtedly develop abdominal cancer and leukemia," Nicholas wrote "It may not happen tomorrow, but yes, sadly it will happen."

Medical experts are somewhat divided over the usefulness of the so-called virtual colonoscopy, which was designed as a less-invasive alternative to colonoscopy.

The American Cancer Society and the American College of Radiology endorse the procedure for its potential to boost screening for colon cancer, the country's second leading cancer killer.

But some insurers and the government's own Medicare program refuse to pay for the procedure, questioning its effectiveness and the rationale of exposing healthy patients to radiation.

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