[ RadSafe ] Fw: 'CT Scans May Pose Less Cancer Risk Than Thought", Study Contends

Stewart Farber radproject at sbcglobal.net
Wed Jan 5 18:58:18 CST 2011

A paper was presented recently at the Radiological Society of North America
 in Chicago which is reported in the general summary news article below.
 It would seem unlikely to be able to derive meaningful conclusions given the time 
frame of the study of records for Medicare patients, and the short 
period of time since the CT scans were used. It is mentioned that the 
conclusions are based on applying "standard risk models" [and not gathering actual
 cancer outcomes in the two groups --which would seem to be irrelevent given the short time since CT exposure], yet cancer risks are said to be 
50 to 100 times lower than expected. If "standard risk models" are used why would the cancer risks be 50 to 100 times "lower than expected"??

And without doubt, any study of excess cancer outcomes, even among millions of Medicare patients receiving CT imaging from 5 to 10 years earlier makes no sense.

It clearly will be necessary to get a look at the paper noted to make any sense of the summary conclusion, which may get a lot of exposure of a different kind before the paper is ever published in a peer reviewed journal in its present form.

The study looked at medical records of elderly patients covered by Medicare between 1998 and
 2005. As noted below:

"The researchers separated the data into two periods: 1998 to 2001 and
 2002 to 2005. In the earlier period, 42 percent of the patients had 
undergone CT scans. For the period 2002 to 2005, that figure rose to 49 

The source of the summary article reproduced below is from the hyperlink after my signature  [scroll down a bit to find it]:

From: http://sacred-heart.privatehealthnews.com/html/topicdetails.asp?pid=146&topic_id=15277&puid=582997

If anyone gets the paper, please let me know and perhaps it could be scanned for interested members to review.

Stewart Farber, MSPH  Farber Medical Solutions, LLCBridgeport, CT 06604(203) 441-8433 [office]website:  www.farber-medical.come-mail:    farber at farber.info

CT Scans May Pose Less Cancer Risk Than Thought, Study Contends
                              SOURCES: Aabed Meer, M.D.-candidate, 
department of radiology, Stanford University, Palo Alto, Calif.; Robert 
Zimmerman, M.D., executive vice chair of radiology, Weill Cornell 
Medical Center, New York City; Dec. 1, 2010, Radiological Society of 
North America meeting, Chicago 
 Dec. 1 (HealthDay News) -- The risk of developing cancer as a result of
 radiation exposure from CT scans may be lower than previously thought, 
new research suggests.
That finding, scheduled to be presented Wednesday at the annual 
meeting of the Radiological Society of North America in Chicago, is 
based on an eight-year analysis of Medicare records covering nearly 11 
million patients.
"What we found is that overall between two and four out of every 
10,000 patients who undergo a CT scan are at risk for developing 
secondary cancers as a result of that radiation exposure," said Aabed 
Meer, an M.D. candidate in the department of radiology at Stanford 
University in Palo Alto, Calif.
"And that risk, I would say, is lower than we expected it to be," said Meer.
As a result, patients who need a CT scan should not be fearful of the consequences, Meer stated. 
"If you have a stroke and need a CT scan of the head, the benefits of
 that scan at that moment outweigh the very minor possibility of 
developing a cancer as a result of the scan itself," he explained. "CT 
scans do amazing things in terms of diagnosis. Yes, there is some 
radiation risk. But that small risk should always be put in context."
The authors set out to quantify that risk by sifting through the 
medical records of elderly patients covered by Medicare between 1998 and
The researchers separated the data into two periods: 1998 to 2001 and
 2002 to 2005. In the earlier period, 42 percent of the patients had 
undergone CT scans. For the period 2002 to 2005, that figure rose to 49 
percent, which was not surprising given the increasing use of scans in 
U.S. medical care.
Within each group, the research team reviewed the number and type of 
CT scans administered to see how many patients received low-dose 
radiation (50 to 100 millisieverts) and how many got high-dose radiation
 (more than 100 millisieverts). They then estimated how many cancers 
were induced using standard cancer risk models. 
Yet despite the upward trend in the overall use of CT scans, with an 
apparent doubling of both low- and high-dose radiation exposure within 
the two time frames, the researchers determined that there was a 
"significantly lower risk of developing cancer from CT than previous 
Cancers associated with radiation exposure were estimated to be 0.02 percent of the first group and 0.04 percent of the second.
Previous estimates ranged from 1.5 percent to 2 percent, said the authors.
While the results are good news, the consequences of CT scans should continue to be monitored, the authors concluded.
Dr. Robert Zimmerman, executive vice chair of radiology at Weill 
Cornell Medical Center in New York City, said that assessing CT scan 
risk is a tricky endeavor. He believes patient needs should be assessed 
on a case-by-case basis so as to limit exposure as much as possible.
"It doesn't surprise me that the secondary cancer risk is low," he 
said. "But it's a very complicated epidemiological notion to deal with. 
Does every amount of cancer radiation exposure increase your risk, or is
 there a level of exposure that your body can always tolerate and 
recover from? It's very, very hard to say," Zimmerman pointed out.
"For better or worse we are now conducting an experiment on the 
entire population of the U.S. as to whether or not low-dose radiation 
exposure is going to raise risk of developing cancer," he said.
Reducing radiation doses across the board should be the goal, 
regardless of the study's finding, he noted. "We always want to make 
sure that the dose used when scanning is as low as possible, and that 
scanning only takes place when necessary and beneficial to the patient,"
 he said.
Because this study was presented at a medical meeting, the findings 
should be viewed as preliminary until they are published in a 
peer-reviewed journal.
More information
For more on CT scans, visit radiologyinfo.org.

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