Mammograms have long been the gold standard for detecting breast
cancer, but they still miss as much as 15 percent of tiny tumors,
usually located in dense breast tissue. Traditionally, MRI's have been used in high risk women or those with dense breasts, but it gives many
false alarms that lead to unnecessary biopsies.
Step forward molecular breast imaging, or MBI, as the latest new experimental approach for detecting cancer in the 25 percent of women over
the age of 40 who have dense breasts. Doctors hope MBI will
prove more accurate and cost less; under $500 versus more than $1,000
for an MRI.
On a mammogram too much healthy dense tissue
lights up, limiting doctors' ability to see small tumors. But with
molecular breast imaging, women receive an injection of a short-acting,
"radioactive tracer" that travels through the body and "latches on" to
cancer cells. The revolutionary new cameras can then detect small
tumours that mammograms often miss.
Although the method is experimental at present, the technique looks promising as a complimentary diagnostic to mammography in those women with dense breasts or who are a high risk.
In one study reported by the Mayo Clinic, 940 women with both MBI and mammography were screened. All
women had dense breasts or some other increased risk factor related to
cancer, such as family history or genetic mutation. Thirteen tumours were detected in 12 patients. Eight of those were
detected by MBI and one by mammography. When used together, MBI and
mammography detected 10 tumours.
Larger trials are needed to further validate the research, but it is
encouraging to find that MBI can detect cancers that are not easily
visible on screening mammography. The next step will be to compare MBI
prospectively to other screening methods such as MRI.