Newer breast imaging techniques pose greater risk for cancer
MedWire News: Newer breast imaging techniques such as breast-specific gamma imaging (BSGI) and positron emission mammography (PEM) have a much greater risk for radiation-induced breast cancer than mammography, study findings indicate.
"The risks and benefits of screening mammography are under constant scrutiny," says R Edward Hendrick (University of Colorado-Denver, Aurora, USA).
"An obvious risk, and a barrier to some women undergoing screening mammography, is the risk for radiation-induced breast cancer," he adds.
To estimate the lifetime risk for radiation-induced cancer incidence and death from breast imaging examinations using ionizing radiation, Hendrick reviewed recent studies on radiation doses from radiologic procedures and organ doses from nuclear medicine procedures, along with Biologic Effects of Ionizing Radiation (BEIR) VII age-dependent risk data.
He found that two-view digital mammography and screen-film mammography involved average mean glandular radiation doses of 3.7 and 4.7 mGy, respectively. These techniques were associated with an average lifetime risk for 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 one million women aged 80 years at exposure.
Overall, annual screening mammography (digital or screen-film) performed in women from age 40 to age 80 years was associated with a lifetime risk for fatal breast cancer of 20 to 25 cases in 100,000.
In contrast, a single breast-specific gamma imaging (BSGI) examination was estimated to involve a lifetime risk for fatal cancer 20 to 30 times (26-39 cases per 100,000) that of digital mammography in women aged 40 years, while the lifetime risk for a single PEM was 23 times (30 cases per 100,000) greater than that for digital mammography.
Hendrick also points out that while mammography only slightly increases a woman's risk for breast cancer, BSGI and PEM may increase the risk of cancers in other organs as well, including the intestines, kidneys, bladder, gallbladder, uterus, ovaries, and colon.
He concludes in the journal Radiology: "When referring patients for recently introduced breast imaging studies such as BSGI and PEM, one should consider the radiation risks as well as the potential benefits of these modalities."
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By Laura Dean