Magnetic Resonance Imaging Morphologic Features of Advanced Breast Cancer Predict Surgical and Pathologic Outcomes after Neoadjuvant Chemotherapy.
Authors: Rosen M. , Marques H. , Herman B. , Mies C. , DiMichele A. , Partridge S. , Lehman C. , Gatsonis C. , Esserman L. , Hylton N. 
Published: December 2010

Background: Neoadjuvant therapy is becoming more widely used for locally advanced breast cancer. Magnetic resonance imaging (MRI) has been shown to be the most accurate imaging modality to determine initial extent of disease, early disease response to therapy, and residual viable tumor at completion of therapy. However, the relationship between the morphologic tumor patterns on MRI and clinical outcomes have not been widely studied. Materials and Methods: A total of 237 women with locally advanced breast cancer were enrolled in CALGB150007/ACRIN6657, a multi-institutional study of serial MRI imaging during neoadjuvant therapy. All women received four cycles of anthracycline-cytoxan (AC) therapy, with the majority also receiving four subsequent cycles of paclitaxel (T) therapy, followed by surgery. Residual cancer burden (RCB) was determined by central pathology review. MRI was performed at baseline, after AC#1, after AC#4, and before surgery. MRI morphologic features at baseline were scored locally by the site radiologist on a five point scale, indicating increasing degrees of tumor dispersion. Longest diameter lesion sum (LD) and volumetric tumor measures were obtained at each time point. Percent deviation of tumor from ideal sphere (%dev) was calculated by dividing the true MRI volume to that of the idealized spherical volume: (4π/3)*(LD/2)3, and subtracting from 100%. Results: Imaging results were available for 215/237 women. Of these, surgical management information and RCB results available for 207 and 194 women, respectively. Women with either type 1 (unifocal confined mass) or type 2 (multi-lobular mass) morphology were more likely to receive lumpectomy over mastectomy (53 vs. 40, 57% breast conservation rate), than were women whose disease was less confined prior the chemotherapy (36 vs. 75, 32% breast conservation rate, p&lt;0.001 for difference between morphology groups). In addition, women with confined disease at baseline (morphology type 1 or 2) demonstrated lower RCB at surgery (RCB=1.60) than those with more dispersed baseline morphologies (RCB=2.04, p=0.042). Percent deviation from idealized spherical volume at baseline was greater for patients with more dispersed morphologies (%dev=81%) than for those with contained morphologies (%dev=51%, p&lt;0.001). This difference decreased after four (74% vs. 85%, p=0.013) and eight cycles of chemotherapy (76% vs. 85%, p=0.023). Discussion: Baseline tumor morphology by MRI is a strong predictor of RCB following neoadjuvant chemotherapy, and can be used to gauge likelihood of successful down-staging of tumor for potential breast conservation therapy. Radiologist-graded tumor morphologies detect differences in tumor deviation from ideal spheres at baseline, although this distinction decreases as tumors respond to neoadjuvant chemotherapy. Supported by NIH grant CA080098

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4016.