Clinical Analysis of Medullary Carcinoma of the Breast

Purpose Medullary carcinoma of the breast is a variant of breast cancer characterized by the histologic appearance of poorly differentiated cells surrounded by a prominent lymphoid stroma. Medullary carcinoma has been reported to carry a prognosis better than other invasive breast carcinomas, but it is frequently overdiagnosed due to the difficulty in diagnosis. The aim of this study was to assess the clinical manifestations and outcome of medullary carcinoma of the breast. Methods We reviewed the data of 91 patients diagnosed with medullary carcinoma and 3,743 patients with invasive ductal carcinoma, not otherwise specified (NOS) from January 1980 to December 2005 at Yonsei University Severance Hospital. The clinicopathologic features, disease free survival (DFS) and overall survival (OS) for patients with medullary carcinoma were compared with those of the NOS patients. Results With reviewing the pathologic slides, 69 (75.8%) patients had findings compatible with typical medullary carcinoma (TMC) and the remaining 22 (24.2%) patients were reclassified as atypical medullary carcinoma (AMC). Early stage cancer was more frequent at medullary carcinoma and lymph node positive cancer was less frequent at medullary carcinoma. The expression of ER/PR was positive in either the TMC (18.9%/16.2%) and AMC (15.0%/20.0%) as compared to the NOS (63.2%/57.2%), and the difference was significant (p<0.001). In contrast, the HER-2/neu expression rate was significantly higher in the TMC (47.4%) and AMC (45.5%) than in the NOS (28.3%, p=0.001). The 10-year disease free survival and 10-year overall survival of the atypical medullary carcinoma patients (67.8%, 77.8%) were in fact similar to the NOS carcinoma patients (68.3%, 74.7%). There was significant difference in 10-year disease free survival and 10-year overall survival between the TMC (77.8%, 86.0%) and NOS carcinoma (68.3%, 74.7%) patients (p=0.002, p=0.006). Conclusion The clinical outcome of typical medullary carcinoma is favorable in spite of its aggressive pathologic features and it differs from atypical medullary carcinoma. For precise prediction of prognosis of medullary cancer, we should apply strict criteria for the diagnosis of subtype with medullary features.