Damian McNamara

April 25, 2016

LOS ANGELES — The lifetime costs associated with the treatment of cancers induced by the ionizing radiation in CT imaging over just 1 year in the United States add up to hundreds of millions of dollars, new research suggests.

"CT imaging has a small theoretical risk of inducing cancer," said Matthew Covington, MD, from the University of Arizona College of Medicine in Tucson. However, "the costs of treating even a proportionately small number of CT-induced cancers may be significant, given the high expense of cancer treatment," he told Medscape Medical News.

So he and Phillip Kuo, MD, PhD, also from the University of Arizona College of Medicine, set out to quantify the problem.

The pair conducted a meta-analysis of published studies to determine the number of CT scans performed in 2012, as well as the risk, prevalence, and incidence of cancer. That year, $87.5 billion was spent to treat 15.5 million adults with cancer, so the per patient annual expenditure was $5631, they calculated.

But the message is not only about money. "Providing the first estimates of these costs allows more accurate economic valuation of CT imaging and argues for continued dose reduction," Dr Covington explained. He presented the findings here at the American Roentgen Ray Society 2016 Annual Meeting.

Calculating Costs

The risk for CT-induced cancer during the average lifetime of a patient is 5.5 of 10,000, or 0.00055%, the researchers estimated. They used the 85 million scans conducted in 2012 to approximate that CT exams caused 46,750 malignancies over the lifetime of the patient population.

They then calculated overall additional costs. When the $5631 per patient annual cost was multiplied by the approximately 43,000 to 46,000 patients with cancer attributable to CT in 2012, they arrived at an annual cost of $244 million to $263 million.

"The small rate of induced cancers attributable to CT has a large and hidden financial cost that may amount to billions of dollars over several years," the researchers point out.

Drs Coving and Kuo laud efforts to reduce patient exposure to radiation, such as the development of newer CT technology that produce effective images at smaller doses.

"Our estimates also predict cost savings that could offset added costs from abdominopelvic MRI — as an alternative to CT — and state-of-the-art low-dose CT scanners," Dr Covington said.

Study Criticism and Response

"This is an economic exercise, but the model lacks many important components," said session comoderator Tessa Sundaram Cook, MD, PhD, from the Hospital of the University of Pennsylvania in Philadelphia.

It is not known how many of the 85 million CT scans were performed after cancer had been diagnosed, Dr Cook told Medscape Medical News. Also, the analysis only includes adults, and "we know that the risk of adverse effects from ionizing radiation is higher in the pediatric population and in young women," she explained.

Dr Covington pointed out that "it has been estimated that one in 10 Americans undergoes a CT scan every year. This suggests that many Americans are undergoing CT for reasons other than cancer imaging."

"The high volume of CT performed in the emergency setting has also been well documented. Furthermore, even if a CT is performed after a cancer diagnosis, these patients may still be at risk of developing a second CT-induced cancer, particularly if patients are young or have treatable disease," he added.

In fact, "including pediatric patients in our cost analysis would likely increase our cost estimates because children are known to be at higher risk of developing cancer from CT radiation than adults," Dr Covington told Medscape Medical News.

Dr Cook said that "the assumption is that all CTs contribute to cancer risk and that the risk is avoidable, but there is no consideration of the benefit to the patient."

Benefits and Risks of CT

"We agree that CT is lifesaving technology that prolongs health by facilitating rapid diagnosis in the appropriate clinical setting," Dr Covington said. But "even when used appropriately, CT should be performed at the lowest possible dose." He added that "patients who understand the risks and benefits of CT imaging are in the best position to consult with their physicians to ensure that CT imaging is appropriately used and performed as safely possible."

Dr Cook said that "although Dr Covington tried to promote the more routine use of MRI over CT to mitigate the risk for radiation-induced cancer during his presentation, the researchers did not note that MRI has its own risks, such as for patients with metal or other implants, claustrophobia, and motion sensitivity, in addition to long imaging times."

Even when used appropriately, CT should be performed at the lowest possible dose.

Although MRI is not risk-free, no evidence suggests that MRI causes cancer, Dr Covington explained. "For this reason, MRI is considered a safer way to image many pediatric patients and pregnant women in particular."

The meta-analysis used data from the BEIR VII report to extrapolate risk for cancer after exposure to medical imaging, numbers of CT-induced cancers, and the financial cost of radiation when correlated with the cost of cancer treatment, Dr Cook said. However, "the data reported in BEIR VII are not intended to be used in this manner. The commission's members clearly state in the report that there is statistical analysis but also a significant amount of opinion that contributed to the final conclusions."

Models of the risks related to radiation are built from limited data and, therefore, inherently controversial; nonetheless, BEIR VII risk estimates are perhaps the best known and most widely used risk estimates, Dr Covington said. "We used BEIR VII data in a novel way to estimate the direct cancer treatment costs of CT-induced cancer. We encourage researchers to compare our results with other risk estimates."

"We do not want to convey a message to our patients that the money they spend on their healthcare should not be spent on imaging or to promote the misinformation that skipping an imaging study is somehow better for their health than 'risking' the radiation exposure," she emphasized.

"Our cost estimate is the first of its kind and should be considered a starting point for future estimates of this important variable," Dr Covington said. "Many radiologists and other professionals have collectively worked to lower CT doses and advance MRI as a viable alternative to CT. Understanding the true costs of CT — including the cost of treating CT-induced cancers — will continue to drive this trend."

Dr Covington and Dr Cook have disclosed no relevant financial relationships.

American Roentgen Ray Society (ARRS) 2016 Annual Meeting: Abstract 1576. Presented April 21, 2016.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.