Breast cancer tumor size: correlation between magnetic resonance imaging and pathology measurements

Background As physicians increasingly use magnetic resonance imaging (MRI) for the evaluation of newly diagnosed breast cancers, a review of the correlation between MRI and pathology tumor size is imperative. Methods A retrospective review of 91 breast tumors comparing preoperative MRI tumor size to final pathology tumor size was performed. Results MRI and pathology tumor size were positively correlated (R = .650), but with an average overestimation by MRI of .63 cm (P <.0001). When stratified by MRI tumor size (≤2.0 cm and >2.0 cm), a significant difference was found only in tumors greater than 2.0 cm (average overestimation = 1.06 cm; P <.0001). This trend continued for the histological subtypes of ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), and invasive lobular carcinoma (ILC). Conclusions MRI tumor size correlates with pathology size; however, a significant overestimation exists, particularly for tumors >2.0 cm. Clinicians should therefore use caution in relying on MRI tumor size in determining candidacy for breast conservation therapy (BCT).