Minn. – For women with dense breast tissue, supplementing
standard mammography with a new imaging technique called
molecular breast imaging (MBI) can lower the cost of diagnosis
of breast cancers, according to a Mayo Clinic study published
in the American Journal of Roentgenology (AJR).
at the Mayo Clinic Center for Individualized Medicine found
that adding MBI to mammography of women with dense breast
tissue increased the costs of diagnosis 3.2 times, compared to
costs of mammography alone, and nearly quadrupled the rate of
cancer detection. Because the supplemental test found more
cancer, screening with a combination of mammography and MBI
saved $8,254 per cancer detected.
mammography is still the standard tool for widespread breast
cancer screening, it is now known to perform less effectively
in women with dense breast tissue. Both tumors and normal
dense breast tissue can appear white on a mammogram, making
tumors hard to detect. Nearly half of all women over age 40
have mammograms classified as "dense," according to
Carrie Hruska, a medical physicist in the Mayo Clinic
Department of Radiology and the study’s lead author.
Supplemental screening techniques like MBI address a
significant need for better cancer detection methods for this
MBI examination, a radioactive tracer readily absorbed by
cancerous breast cells is injected into the body. A small,
semiconductor-based gamma camera then scans the breast,
lighting up any areas where the tracer is concentrated.
"It works really well in our practice at Mayo
Clinic," Hruska says. "Patients generally like it,
and radiologists think it’s relatively easy to read."
screening combination of MBI and mammography can detect more
cancers than mammography alone at acceptable radiation doses
for screening, as the research group reported in a study
published in AJR in February. But concerns persist about the
cost-effectiveness of MBI. Though the test finds more cancer
in dense breast tissue, additional screening could also
generate more false-positive results and lead to biopsies that
do not result in a cancer diagnosis, ultimately increasing
and her colleagues used the same data from the February study
to compare the cost-effectiveness of screening 1,585 women
with dense breast tissue with mammography alone and the
combination of mammography and MBI. The comparison resulted in
per patient screened increased from $176 to $571 for the
combination of tests. Mammography alone detected cancer in
five of these patients. With the combination, physicians
detected cancer in the first five women and an additional 14
patients, nearly a fourfold improvement.
cost per cancer detected was $55,851 for mammography alone and
$47,597 for the combination of mammography and MBI, a savings
of $8,254 per cancer detected.
of receiving an unnecessary biopsy because of a false-positive
result increased from 0.9 percent with mammography alone to 3
percent with the addition of the MBI examination. However,
this 2.1 percentage point increase in the benign biopsy rate
is lower than the 6-point increase observed in outside studies
using screening ultrasound or screening MRI, two alternative
positive predictive value (PPV) of MBI, or the likelihood that
a biopsy generated by MBI would result in a cancer diagnosis,
was 30 percent. In contrast, biopsies generated by screening
ultrasound and MRI have PPVs of 6 percent and 20 percent,
saving per cancer detected with supplemental screening MBI is
compelling evidence for future coverage of screening MBI of
women with dense breasts," the authors write. The study
did not consider any costs beyond the point of cancer
detection; however, the authors speculate that earlier
detection with MBI may reduce the costs of treatment of
advanced cancer further. When dense breast tissue is the only
criterion for supplemental imaging like MBI, insurance
coverage varies from state to state and among insurance
providers. Hruska calls the latest study a critical step in
developing MBI as an individualized screening approach for
patients with needs unmet by current options.
question is: What’s the right screening regimen for
you?" says Hruska. "For about half of women of
screening age, mammography works well. The other half —
those with dense breasts — may want to consider adding
another test. If you have additional risk factors, like family
history or a genetic mutation that predisposes you to breast
cancer, then you should have a supplemental MRI. But there’s
this huge group of women in-between who don’t qualify for a
supplemental MRI and need something more than a mammogram.
That’s who we’re trying to reach."