Dynamic MRI Detects Multicentric/Multifocal Cancer

ORLANDO—Dynamic magnetic resonance imaging (MRI) can identify women who have unsuspected multicen-tric/multifocal breast cancer and are therefore not candidates for breast conservation therapy, Michael J. Kerin, MD, reported in a plenary presentation at the 52nd Annual Cancer Symposium of the Society of Surgical Oncology (SSO).

Dr. Kerin demonstrated that images produced by dynamic MRI are better than those from conventional mammography. Dynamic MRI does not require compression of the breast, and the resulting images are particularly sensitive for detecting multicentric or multifocal disease.

Dynamic MRI vs Triple Assessment

Dr. Kerin reported data comparing the sensitivity and specificity of dynamic MRI with that of conventional triple assessment (clinical, cytological, and mam-mographic examination) in 334 women with symptomatic breast disease.

The work was done in collaboration with S. Chatpadhyay and other researchers at the University of Hull Academic Surgical Unit and the Centre for MR Investigations, Hull, United Kingdom. This prospective study was inspired by the fact that mammography examinations miss about one-third of cases of multifocal breast disease.

All patients underwent triple assessment and dynamic MRI with gadolinium contrast, using a 1.5 T whole body imager with phased array bilateral breast coils. Of the 334 patients, 156 had benign disease. The 178 with primary malignancies included 50 (28%) with multifocal or multicentric tumors on histologic examination (Table).

“Standard mammography did not detect multifocal disease in any patient and, in fact, only detected multicentric disease in 25% of patients who had that sort of disease,” Dr. Kerin said.

Dynamic MRI detected all instances of multicentric and multifocal disease but also gave false-positive readings for multifocal disease in 18 of 178 patients (10%). However, 15 of those 18 did have unifocal invasive breast cancer detected on conventional triple assessment.

“Triple assessment had a very poor sensitivity. By contrast, dynamic MRI had a sensitivity of 100% with a reduced specificity because of the false-positive detection of multifocal disease,” Dr. Kerin said.

Because dynamic MRI is expensive and because of the false-positive problems, Dr. Kerin emphasized that a prospective, randomized, controlled clinical trial of dynamic MRI vs triple assessment is needed and that the overall effect on local control and on survival remains to be determined.

For example, Dr. Kerin suggested that more accurate diagnosis of multifocal/multicentric disease might reduce the number of patients who receive breast-conserving therapy but then must undergo additional surgery to remove residual disease. However, a member of the audience challenged the clinical relevance of this point by pointing out that the local recurrence rate in patients treated with lumpectomy plus radiation therapy is only about 10%.