610 Background: Magnetic Resonance Imaging (MRI) of the breast shows superior ability to visualize the extent of invasive breast cancer compared to conventional breast imaging. Nonetheless, MRI may under- or overestimate the extent of invasive disease, and the ability of MRI to depict components of disease around the primary invasive tumor is not well established. The purpose of this study was to precisely correlate MRI findings with histopathologic findings in breast cancer patients and to establish the incidence and quantity of surrounding MRI occult disease in breast cancer patients that are scheduled for breast-conserving therapy (BCT). Methods: Patients were prospectively included if they had biopsy-proven invasive breast cancer and the choice of treatment was BCT after pre-operative MRI. Pathology findings were spatially reconstructed and correlated with preoperative MRI. Tumors were stratified by absence or presence of an extensive intraductal component (EIC- or EIC+). The largest diameter of the MRI-visible lesion was compared with the largest diameter of the primary invasive tumor at pathology. Distances (mm) between the edge of the MRI-visible lesion and surrounding subclinical tumor foci (i.e., DCIS, invasive foci) were measured. At various distances from the edge of the MRI-visible tumor, the incidence of disease was determined. Results: 53 patients with 54 breast tumors were included. 42 tumors were EIC- and 12 were EIC+. The mean size (± SD) of the primary invasive tumor was 18.1 ± 7.5 mm on MRI and 19.5 ± 8.2 mm on pathology (Pearson's correlation coefficient: 0.75). The MRI-visible lesion was larger than or equal to the primary invasive tumor on pathology in 21 (39%) cases. Underestimation of the primary invasive tumor occurred up to 7 mm from the edge of the MRI-visible lesion. Beyond 10 mm, subclinical tumor foci were found in 48% off all tumors, in 36% and 92% of EIC- and EIC+ tumors (p < 0.001). Beyond 20 mm these rates were 19%, 7% and 67%, respectively (p < 0.001). Conclusions: Disease around MRI-visible lesions may be more extensive than assumed prior to treatment, especially in EIC+ tumors. This may have consequences for treatment margins in MRI-guided therapy of localized breast cancer. No significant financial relationships to disclose.
The prognostic significance of BMI1 expression in invasive breast cancer is dependent on its molecular subtypes
