Alternating mammography and magnetic resonance imaging (MRI) at six-month intervals can detect breast cancers not picked up by mammography alone, reports a research team from the University of Texas M.D. Anderson Cancer Center at the San Antonio Breast Cancer Symposium.
The current standard is annual testing which includes a mammogram, MRI and clinical breast exam.
MRIs pick up more abnormalities than mammograms, but they also have a higher rate of returning a false positive result, a suspicious spot that a biopsy shows isn't cancer.
“We were unsure if staggering screening would pick up more cancers,” says study author Huong Le-Petross, M.D., a radiologist at the University of Texas M.D. Anderson Cancer Center. “We were searching for an alternative to offer women screenings every six months, rather than once a year.”
The pilot study involved alternating methods between 334 women, 86 of which were high-risk. Mammograms detected three to nine cancers in high-risk women, and they were confirmed by MRI. Five were detected on MRI, but didn’t show up on mammogram and one tumor was missed by both tests. Overall, MRI detected the majority of tumors.
“MRIs saw the most cancers and the size was relatively small,” that makes them easier to treat, says Le-Petross.
“It does make sense for high-risk women to have some sort of screening in six-month intervals,” says William Audeh, M.D., an oncologist developing a breast-risk-reduction program at Cedars Sinai Medical Center in California. MRIs are undoubtedly the most effective tool available for screening women in this group, he adds.
So, why then, use both tests? If MRIs are effective, why not drop mammograms and have an MRI twice a year? Le-Petross plans to find out by comparing MRI-only routine against the current standard to find out.
Mammograms, however, do offer a special edge over MRIs. They can pick up microcalcifications, notes Audeh. Microcalcifications are tiny bits of calcium that may show up in clusters or patterns (such as lines or circles) on a mammogram that are associated with extra cell activity in breast tissue. In most cases extra cell growth is not cancerous, but tight clusters can indicate early breast cancer. Scattered microcalcifications are usually a sign of benign breast tissue.
Another reason MRIs can’t be the standalone option is insurance companies follow American Cancer Society guidelines for breast screening, which currently recommends one MRI and mammogram a year for women who have a lifetime breast cancer risk of 20 percent or higher.
Women in the high-risk group generally have multiple breast and ovarian cancer cases in the family and/or a positive result on a BRCA breast cancer gene-mutation test, personal history with the disease or a positive biopsy.
Doctors’ advice has long been regular screenings for women that fall into one of these categories. Now, annual visits are no longer a careful, conservative option, but rather the minimum.
The National Cancer Institute estimates 184,000 new cases of breast cancer will be diagnosed in the U.S. in 2008, of them, 41,000 women will die of the disease.
Another study presented at the San Antonio Breast Cancer Symposium, compared dense and non-dense tissues taken from healthy participants, with no history of breast cancer. Researchers found dense breast tissue contains more cells known to produce breast cancer than that of non-dense tissue. #