Accuracy of breast MRI in predicting tumor extent.

Abstract

Abstract Abstract #4022 Introduction: The use of breast MRI to delineate tumor extent prior to surgical resection is becoming more commonplace. How well breast MRI predicts tumor size and extent compared to standard breast imaging is still under investigation.
 Objective: To determine which imaging modality; mammogram (MGM), ultrasound (U/S), or MRI most accurately predicted tumor size and number of tumor foci.
 Methods: This was a retrospective review of a prospectively collected database of all breast MRIs performed prior to surgical resection for invasive and noninvasive breast cancer. MGM, U/S, and MRI reports were reviewed and correlated with pathologic tumor size and number of foci.
 Results: A total of 89 patients with breast cancer underwent bilateral breast MRI prior to surgical resection. Sixty (67%) of the tumors were ductal carcinomas, 21 (24%) were lobular carcinomas, 7 (7%) ductal carcinoma in situ and 2 (2%) were mixed ductal and lobular. The mean tumor size was 1.5cm (0.1-6.0cm) and 32 (38%) were node positive. Fifty three (60%) of the patients underwent lumpectomy and 36 (40%) underwent mastectomy. Of the three imaging modalities, MGM, U/S, and MRI; MRI predicted tumor size significantly more accurately then MGM or U/S (correlation coefficient 0.59 vs 0.78 vs 0.81 respectively). MRI also predicted the number of foci significantly more accurately then MGM or U/S (correlation coefficient 0.48 vs. 0.44 vs. 0.26 respectively). MRI overestimated tumor size by at least 1cm in 12 (14%) patients and the number of tumor foci in 11(16%) patients.
 
 Thirteen (15%) of the patients benefitted from MRI while 14 (16%) did not.
 Conclusions: MRI predicted tumor size and number of foci more accurately then MGM or U/S. Despite these findings, MRI overestimated tumor size and number of tumor foci in a greater percentage of patients then MGM or U/S. More studies are needed to determine the true value of MRI for preoperative surgical planning. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4022.