MRI Detects Invasive Cancers Not Seen on Mammography

Additional breast cancers detected by MRI may be larger and more invasive than those found on mammography, according to a study published online in Radiology.

Researchers from Italy and the United States performed a retrospective study to review MRI images and pathologic features of multicentric cancer detected by MRI only, and to evaluate its potential biologic value.

“Patients with clinically insignificant cancers undergoing potential overtreatment versus patients who may be undertreated is at the heart of the controversy surrounding breast MRI,” lead author Chiara Iacconi, MD, of the Breast Unit at USL1 Massa-Carrara in Carrara, Italy, said in a release.

The records of 2,121 patients were included in the study. All had been newly diagnosed with breast cancer and had undergone biopsy after preoperative MRI. A total of 285 (14%) of the women had additional cancer detected at MRI that was occult at mammography. MRI identified 87 cancers in 73 patients (3.6%) in different quadrants than the known index cancer. One additional cancer was found in 62 of the 73 patients, and multiple additional cancers in the other 11.

The researchers found that multicentric cancer detected only at MRI was:

• Invasive in 66 of 87 patients (76%)

• Larger than 1 cm in 18 of 73 patients (25%)

• Larger than the known index cancer in 17 of 73 patients (23%)

• More biologically important in four of 73 women (5%)[[{"type":"media","view_mode":"media_crop","fid":"44554","attributes":{"alt":"MRI","class":"media-image media-image-right","id":"media_crop_6091381462879","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4999","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 128px; width: 171px; border-width: 0px; border-style: solid; margin: 1px; float: right;","title":"©nav/Shutterstock.com","typeof":"foaf:Image"}}]]

They also found additional cancers in heterogeneously or extremely dense breasts in 59 of 73 patients (81%). In 14 of 73 patients, additional cancers were found in breasts that were classified as predominantly fatty or having scattered fibroglandular tissue.

At mammography, the breasts:

• Were predominantly fatty in two of 73 patients (3%)

• Contained scattered fibroglandular tissue in 12 of 73 patients (16%)

• Were heterogeneously dense in 47 of 73 patients (64%)

• Were extremely dense in 12 of 73 patients (16%)

“We believe invasive cancer larger than 1 centimeter is clinically relevant disease,” Iacconi said in the release. “In general, it is accepted that radiation can likely treat invasive cancer less than 1 centimeter, but lesions larger than 1 centimeter, especially invasive carcinomas, may not be reliably treated with conservation.”

The authors concluded that multicentric cancer detected on breast MRI after mammography appears to represent a larger tumor burden in approximately a quarter of patients, which may result in potential changes to cancer grade and treatment, Iacconi said in the release.