MEDULLARY CARCINOMA OF THE BREAST, PROGNOSTIC IMPORTANCE OF CHARACTERISTIC HISTOPATHOLOGICAL FEATURES EVALUATED IN A MULTIVARIATE COX ANALYSIS

In this study of 136 breast cancers with medullary features (MC), regi stered in the Danish Breast Cancer Cooperative Group (DBCG) from 1982 to 1987, we confirmed the prognostic importance of a new definition of medullary carcinoma of the breast (MC newdef) which was recently prop osed by us, deduced from a previous study of a corresponding tumour ma terial (DBCG 77-82). However, the individual histological criteria did not have the same prognostic importance as in our previous study, alt hough prognostic trends were the same. To further improve and validate the diagnostic criteria, we combined the two populations and performe d a multivariate Cox regression analysis. In the final Cox model, four histological parameters retained positive prognostic importance: (1) predominantly syncytial growth pattern, (2) no tubular component, (3) diffuse stromal infiltration with mononuclear cells and (4) sparse nec rosis. We propose that these criteria are emphasized in the histologic al diagnosis of medullary carcinoma of the breast.