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Nuclear breast imaging tests associated with higher cancer risks

by Heather Mayer, DOTmed News Reporter | August 24, 2010
Two types of nuclear breast imaging scans may actually increase the risk of developing radiation-induced cancers, according to research published today in a special online report and in the October issue of Radiology.

Research conducted by Dr. Edward Hendrick, a clinical professor of radiology at the University of Colorado, Denver School of Medicine, found that single breast-specific gamma imaging (BSGI) or positron emission mammography (PEM) carries a lifetime risk of inducing fatal cancer greater than or comparable to a lifetime of annual screening mammography, starting at age 40.

“Not all breast imaging procedures carry the same doses and risks as mammography,” Hendrick told DOTmed News. “Physicians prescribing these studies need to be aware of the risk and inform the patients of those risks.”

Both procedures are nuclear imaging tests, injecting radioactive material into patients. In fact, the imaging agent used in BSGI is the same — and the same dose — as the one used in nuclear cardiac stress testing, explained Hendrick. He pointed out that researchers thought if the agent, technetium 99m–sestamibi, was used in other tests it would be safe in BSGI scans.

“But it turns out, it carries a considerably higher dose risk than most other breast procedures,” he said. “The risk is exactly the same between a stress test and BSGI. The point is, most breast imaging procedures, you’re irradiating the breast. The doses to other tissues are very, very minor. With these nuclear procedures, BSGI or PEM, the dose to the breast is relatively modest…but the dose to other organs is not modest by comparison.”

Hendrick, the sole author on the paper, reported that two-view digital mammography and screen-film mammography have an average lifetime risk of fatal breast cancer of 1.3 and 1.7 cases, respectively, per 100,000 women aged 40 years at exposure and less than one case per 1 million among women aged 80 years at exposure. Annual screening mammography in either digital or screen-film in women ages 40 to 80 was found to be associated with a lifetime risk of fatal breast cancer of 20 to 25 cases in 100,000. Dedicated breast computed tomography and digital tomosynthesis — neither FDA-approved — were found to have an average lifetime risk of fatal breast cancer of 1.3 to 2.6 cases, respectively, per 100,000 women aged 40 years at the age of exposure.

The cancer risks from BSGI and PEM were alarmingly higher. Hendrick found that a single BSGI exam was estimated to carry a lifetime risk of fatal cancer 20 to 30 times that of digital mammography in women aged 40 years, and the lifetime risk of a single PEM exam was 23 times greater than that of digital mammography.