MRI shows residual breast cancer disease better than other modalities

Preliminary results from American College of Radiology Imaging Network Trial 6657 show that MRI estimates residual breast cancer disease area better than clinical exams or mammography.

The study is a part of the national I-SPY collaborative trial of imaging and biomarkers for monitoring and guiding preoperative treatment for women with breast cancer.

Nola Hylton, Ph.D., and colleagues examined 216 patients at eight institutions for the trial. The multicenter study examined MRI for measurement of breast tumor response to neoadjuvant chemotherapy.

Women with invasive breast cancer measuring 3 cm or greater who received an anthracycline-cyclophosphamide (AC) neoadjuvant chemotherapy regimen followed by a taxane were enrolled between May 2002 and March 2006. Contrast-enhanced MRI was performed at baseline, following one AC cycle, between AC and taxane treatment, and after taxane treatment but prior to surgery.

Tumor size measurements included clinical size, mammographic longest diameter, and MRI volume.

"In univariate and multivariate models, MRI volume change after one cycle of therapy was the only measurement that predicted clinical response," said Hylton, a professor of radiology at the University of California, San Francisco.

Following neoadjuvant chemotherapy, MRI is more accurate than clinical exams or mammography for estimating residual disease and predicting response to treatment, she said.

"Mammography does not appear to add value to this setting," said Hylton, who is also director of the Magnetic Resonance Science Center at UCSF.

The researchers are continuing to collect follow-up data to test MRI's ability to stratify post-treatment risk groups according to three-year disease-free survival. The researchers expect to release final results from the ACRIN trial by June 2009.