CT Scans May Not Be as Risky as Once Thought, Study Finds

A new study suggests cancer risk from CT scans may have been overestimated.

ByABC News
November 30, 2010, 6:02 PM

Dec. 1, 2010— -- Doctors have long known that CT scans can be a double-edged sword. Their diagnostic power is pivotal in modern-day medicine, but their inherent cancer risks leave both physicians and patients wary.

Now, a new study presented at a major scientific meeting may alleviate some CT cancer fears -- but it may also fuel the controversy surrounding the tests.

The study of more than 10 million Medicare patient records suggests that the cancer risks from the scans are much smaller than past studies claim. Prior research estimated radiation-induced cancer rates associated with these scans around 1.5 to 2 percent, but results from the Stanford study found that CT scans were only associated with a 0.02 to .04 percent higher risk of cancer in its study population.

"The bottom line here is that not enough work has been done in this area yet," said Dr. Pat Basu, faculty radiologist at Stanford University and co-author of the study. "We need to be sure not to over-scan people, but not forget the tremendous benefits from CT scans; they can save lives and make medical care cheaper."

Researchers studied data from more than 5 million Medicare data records from 1998 to 2001 and more than another 5 million records from 2002 through 2005.

CT scans of the head were found to be the most common examination from the data, but abdominal CT scans brought on the highest amount of radiation for patients.

"CT scans do put you at risk of cancer, the question is how much," said Dr. Carl Schultz, professor of emergency medicine at UC Irvine School of Medicine and director of research at the Center for Disaster Medical Sciences. "This seems to be a more accurate estimation of the population's risk because it takes into account how CT scans are used in the population."