Does size matter? Comparison study between MRI, gross, and microscopic tumor sizes in breast cancer in lumpectomy specimens

Size of breast cancer is essential in staging cancer to determine type and extent of patient management. This study was conducted to assess accuracy in estimating tumor size by MRI and gross using microscopy as gold standard. A retrospective study was done on 33 patients, 30-75 years, who underwent MRI of breasts with subsequent lumpectomy, 2002-2006, for invasive breast cancer. Size of lesion(s) on MRI and gross were compared with histological size. Of 37 lesions, 27 (73%) were invasive ductal (IDC) and 10 (27%) invasive lobular carcinoma (ILC). Tumor size by MRI matched histological size in 3%, underestimated 27%, and overestimated 70% of cases. Tumor size by gross matched histological size in 22%, underestimated 57%, and overestimated 22% of cases. MRI as an imaging modality and gross pathology both have significant limitations in measuring tumor size particularly in cases of invasive breast carcinoma. Random sectioning of lumpectomy specimen in invasive breast carcinoma may result in inaccurate staging of tumor by leading to false impression of tumor size and multi-focality and/or multi-centricity of tumor particularly in cases of ILC. Microscopic measurements of tumor size are necessary for accurate T-staging and recommended for appropriate patient management