Navigation Links
Coronary Calcium Scans Can Raise Cancer Risks
Date:7/13/2009

But study finds wide range of doses, lack of protocols for this screening test

MONDAY, July 13 (HealthDay News) -- When weighing whether a coronary calcium scan is worth the risk, a new study suggests that arriving at an answer won't be clear-cut or easy.

A team of researchers from the U.S. National Cancer Institute and Columbia University found that the average range of radiation exposure from having such a screening test every five years would cause 42 additional cases of cancer among 100,000 men and 62 additional cases among 100,000 women. However, given the wide range of radiation doses seen in the study, the increase could be as low as 14 cases and as high as 200 cases among 100,000 men, and as low as 21 cases or as high as 300 cases among 100,000 women.

This is an issue of growing importance on the American medical scene, said Dr. Andrew J. Einstein, director of cardiac computed tomography research at Columbia University, and a member of a team that reports its findings in the July 13 issue of the Archives of Internal Medicine.

"There has been great interest recently in computed tomography, owing to the fact that the number of CAT scans has grown tremendously in the United States," Einstein said. "The National Council on Radiation Protection & Measurement estimates that 70 million are done per year."

The study in which Epstein took part looked at a form of computed tomography that scans for calcium deposits in heart arteries. CAC scanning, as it is called, is one of the lesser-done forms of computed tomography, but a private organization, Screening for Heart Attack, Prevention and Education, has proposed that it be done annually on 50 million Americans, and a new Texas law mandates health insurance coverage of the procedure.

The new study looked at what a dose of radiation in a single CAC scan would be, and found an enormous variation. There is no single protocol -- set of rules -- for such a scan, which can be done on a variety of equipment, Einstein said. "This was first proposed in 1990, and CT scanner technology has changed, so it is not clear what the protocol might be," he noted.

The study found roughly a 14-fold difference in radiation dosage among the various CAC scan protocols. Eliminate two or three "outlying" readings, and the difference is still threefold, Einstein said.

But those estimates are suspect, said Dr. Thomas G. Gerber, an associate professor of medicine and radiology at the Mayo Clinic, and co-author of an accompanying editorial, because it is based on extrapolation of the damage done to people exposed to high doses of atomic bomb radiation at Hiroshima and Nagasaki.

"At the very low doses used in medical imaging, there is a huge controversy about whether there is an increased risk of anything," Gerber said. "Estimates of increased risk are based on a linear no-threshold hypothesis. There is even a theory that chronic exposure to low doses of radiation might be beneficial."

There is equal cloudiness on the benefit side of the equation, said Gerber. "I am not a strong proponent of screening," he added.

"The risk of cardiac events increases if calcium is present in the arteries," Gerber said. "But you can't pick up blockages before they are 70 percent or more. There is some debate about whether the risk predicted by coronary calcium screening is incremental [adds to] the risk predicted by conventional risk factors. It stands to reason that it might be, but that is not proven."

The U.S. Preventive Services Task Force recommends against using CT scans in screening programs, and the American Heart Association says they should be used for "selected individuals" at intermediate risk.

So what do physicians do about CAC scanning in the real world?

"I like using it for patients at intermediate risk of coronary disease, when I do not know how aggressive therapy should be," Einstein said. "For such patients, it is a fantastic test."

"In my practice I use it for patients with no symptoms but an unfavorable risk factor profile," Gerber said. "If there are risk factors but they are adamant about not changing their lifestyle or taking coronary medication, I think it sometimes helps patients realize their coronary atherosclerosis [hardening of the arteries] has begun."

A definitive study of the risk-benefit ratio of CAC scanning is unlikely, Einstein said. The people in question are not at high risk of heart disease, and "the rarer an event is, the larger the sample size that is needed," he said. "A randomized controlled trial would require hundreds of thousands or millions of patients, with adequate follow-up."

More information

For more on coronary calcium scans, go to the U.S. National Heart, Lung, and Blood Institute.



SOURCES: Andrew J. Einstein, M.D., assistant professor, clinical medicine, and director, cardiac computed tomography research, Columbia University, New York City; Thomas G. Gerber, M.D., Ph.D., associate professor, medicine and radiology, Mayo Clinic, Rochester, Minn.; July 13, 2009, Archives of Internal Medicine


'/>"/>
Copyright©2009 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Use of certain lipid measures not more effective in predicting coronary heart disease
2. Diabetes appears to increase risk of death for patients with acute coronary syndromes
3. Treating depression may improve recovery of heart rate variability following coronary syndromes
4. Proven Terumo Coronary Guidewire Technology Is Now Available in the United States
5. Study Links Coronary Disease, Colon Cancer
6. Coronary Disease Might Toughen Up Heart
7. Stereotaxis Highlights Live Coronary and Peripheral Vascular Cases Performed at TCT With Stereotaxis Magnetic Navigation System
8. Boston Scientific Welcomes FDA Panel Recommendation to Approve PROMUS(TM) / XIENCE(TM) V Everolimus-eluting Coronary Stent System
9. Cardica Announces Live Webcast Demonstrating Breakthrough Device to Facilitate Beating Heart and Robotic Coronary Revascularization Surgery
10. Coronary Artery Calcium May Raise Womens Heart Risk
11. Abdominal Fat Tied to High Risk for Coronary Trouble
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Coronary Calcium Scans Can Raise Cancer Risks
(Date:8/16/2017)... ... ... The next Patient Care Academy at Kalamazoo Valley Community College begins September 5, ... long Patient Care Academy are eligible to take the State of Michigan examination to ... Kalamazoo is $24,428.* , As a CNA, one is equipped for employment in long-term ...
(Date:8/16/2017)... ... 2017 , ... Ten outstanding teachers in the Greater Houston area will be ... a visit by a Houston Texans player, two tickets to a Texans game, and ... can visit texanschecking.com/stars to nominate their favorite teacher with an essay of no more ...
(Date:8/16/2017)... (PRWEB) , ... August 16, 2017 , ... ... Atlanta, opened their doors. They celebrate 30 years in business this year, and ... an up-to-date, inviting, tranquil space to serve their patients. , It stands ...
(Date:8/16/2017)... ... August 16, 2017 , ... Maury Regional Health has announced a ... By broadly deploying AccuVein devices, Maury Regional Medical Center is making vein visualization part ... of a needle stick and more importantly, helps our staff members locate a vein ...
(Date:8/16/2017)... ... August 16, 2017 , ... A global leader in ... opened clubfoot clinics in all 29 Indian states—bringing the country one step closer to ... Himachal Pradesh, the nonprofit organization is on track to enroll 10,000 children in the ...
Breaking Medicine News(10 mins):
(Date:8/10/2017)... LAKEWOOD, Colo. , Aug. 10, 2017  Physical Rehabilitation ... Therapy, located in Lakewood, Colorado . The ... Jeff Lipkin , PT, DPT with his staff of ... the University of Pittsburgh and brings over 10 years of ... Belmar PT marks the 10th PRN clinic ...
(Date:8/7/2017)... , Aug. 7, 2017 Diplomat Pharmacy, Inc. (NYSE: ... Joel Saban as president, effective Aug. 7, 2017. ... has decided to pursue other interests and will serve as ... tenure, Paul has served us in multiple leadership roles since ... in Jun. 2015 and has provided decisive, strategic leadership which ...
(Date:8/3/2017)... -- Opioid addiction and other drugs of abuse, blood poisoning ... outcomes, were problems taken on directly as laboratory professionals, ... them, met this week. This according to Kalorama Information. ... abuse, procalcitonin and acute kidney injury were key focuses ... in San Diego, CA.  Mechanisms ...
Breaking Medicine Technology: