New breast imaging technology raises cancer risk

 Carol Forsloff - According to new research in
radiology new breast-imaging technology may actually raise the risk of
cancer in women, although the risk is low.


A special report in the October issue of Radiology
underlines the risks of new nuclear-based breast imaging exams.  On the
other hand, the dose of radiation and risk from mammography are very
low.

"A
single breast-specific gamma imaging (BSGI) or positron emission
mammography (PEM) examination carries a lifetime risk of inducing fatal
cancer greater than or comparable to a lifetime of annual screening
mammography starting at age 40" said the study’s author, R. Edward
Hendrick, Ph.D..  He is a clinical professor of radiology at the
University of Colorado-Denver, School of Medicine in Aurora, Colorado.

The
risks and benefits of screening mammography are under constant scrutiny
because of the injection of radioactive material into the patient in
these newer breast imaging technologies.

There are other technologies that may be available that may not involve
these issues, but these have not yet been approved by the FDA.

But how risky are these new procedures by comparison with others?

"Two-thirds
of mammography units in the U.S. are now digital, which, on average,
exposes the patient to an even lower radiation dose than screen-film"
Dr. Hendrick said. "Manufacturers and breast centers continue to take
steps to lower radiation doses on digital mammography systems without
negatively affecting image quality"

Scientists
remind us that people are exposed to radiation from natural sources all
the time. The average person in the U.S. receives an effective dose of
about 3 millisieverts (mSv) per year from naturally occurring
radioactive materials and cosmic radiation from outer space.

At
the present time the use of these specialized mammographies is related
to evaluation of those with suspicious breast lesions and in women with
dense breasts difficult to examine with other techniques.   Even though
there is increased cancer risk, the exams have shown promise in
detecting cancer accurately.

"The
primary tool for breast cancer screening is still mammography, which
has a very low radiation dose and a very low lifetime risk of cancer
induction" Dr. Hendrick said. "The risk of missing a breast cancer
because mammography is not done far outweighs the tiny risk of
mammography causing a breast cancer"

He
added that the subset of women under 40 who are known to be at higher
risk of breast cancer should consider being screened with breast
ultrasound or breast MRI, both of which deliver no ionizing radiation
and have sensitivities to breast cancer that are unaffected by higher
breast density.