New Imaging Technique Quadruples Breast Cancer Detection Rates

Technology locates tumors otherwise obscured by dense breast tissue on a mammogram.

A major breakthrough in the detection of breast cancer was made recently by researchers at the Mayo Clinic.

A study published last week in the American Journal of Roentgenology outlines a new breast imaging technique that nearly quadruples the detection rates for invasive breast cancers in patients with dense breast tissue. The technique, called Molecular Breast Imaging (MBI), is a supplemental technology developed to locate tumors that would otherwise have been obscured on a mammogram by surrounding tissue.

"The finding that MBI substantially increases detection rates of invasive cancers in dense breasts without an unacceptably high increase in false positive findings has important implications for breast cancer screening decisions, particularly as 20 states now require mammography facilities to notify women about breast density and encourage discussion of supplemental screening options," senior author Deborah Rhodes, MD, said in a press release. "These findings suggest that MBI has a more favorable balance of additional invasive cancers detected versus additional biopsies incurred relative to other supplemental screening options."

Tumors can be indistinguishable from dense breast tissue during traditional imaging procedures because both can appear to be white on a mammogram. Approximately half of all screening-aged women have dense breast tissue, the researchers noted.

The study enrolled 1585 women with dense breasts who received an MBI exam when they went for a traditional mammogram.

MBI was found to increase the detection rate for invasive breast cancers by more than 360% when combined with regular screening mammography. The new technique utilizes uses small, semiconductor-based gamma cameras that image the breast after injection of a radiotracer that tumors absorb avidly, the study authors noted.

MBI takes advantage of the varying behavior of tumors in relation to the background breast tissue, which generates a functional image that allows tumors not seen on mammography to be detected.

Through MBI, 21 of the women (24%) in the study were diagnosed with cancer. Five were diagnosed through just mammography alone, while 19 were diagnosed through mammography with MBI (91%).

Additionally, there was a significant increase found in the detection of invasive cancers, as a total of 1.9 invasive cancers per 1000 women with mammography and 8.8 per 1000 women with mammography plus MBI was observed. There was not a significant difference found in the rates of detection for noninvasive cancers.

The risk of undergoing an unneeded biopsy due to a false positive exam also increased in the study, rising 1 in 100 women with mammography to 4 in 100 women with mammography plus MBI.

For comparative purposes, alternative supplemental screening techniques, such as ultrasound and MRI, have been previously found to generate approximately 8 additional unnecessary biopsies per 100 women.

"This new study is important because it incorporates many of the advances in MBI pioneered here at Mayo Clinic and shows that studies can be performed safely, with low radiation exposure to the patient," MBI inventor Michael O'Connor, PhD, said in a press release. "This means MBI is safe and effective as a supplemental screening tool."