(CBS) Do the diagnostic tests doctors use to detect breast cancer actually cause cancer?
That's the shocking finding of a new study of some of the newest, most sophisticated imaging techniques, including breast-specific gamma imaging (BSGI) and positron emission tomography (PEM).
While the new techniques can be very helpful in diagnosing some tricky cases of breast cancer, they involve the injection of radioactive material, which increase the risk of developing cancer.
Just how risky are the new procedures?
"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," the study's author, Dr. R. Edward Hendrick, clinical professor of radiology at the University of Colorado-Denver, School of Medicine in Aurora, said in a written statement.
Dr. Hendrick reviewed recent studies on radiation doses from procedures that involve radioactive material to estimate the lifetime risk of radiation-induced cancer and death.
It's no secret that digital mammography, the standard diagnostic test for breast cancer, delivers a small amount of radiation. But Hendrick estimates that a single BSGI exam involves a lifetime risk of fatal cancer 20 to 30 times greater in women aged 40 years.
The lifetime risk of a single PEM is 23 times greater than that of digital mammography, according to his work.
In addition, 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.
The new tests are used primarily in women with dense breasts that are difficult to examine with other techniques.
"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."
The study was published in the journal Radiology.