Pathobiologic identification of two distinct breast carcinoma subsets withdiverging clinical behaviors

Many different pathological and biological variables which characterize bre ast carcinomas have been found to be associated. The aim of this work was t o analyze the complex relationship among these parameters. The pathologic, biologic, and clinical characteristics of a series of primary breast carcin omas from 676 patients were retrospectively investigated. Multiple correspo ndence analysis of 13 factors revealed clustering of eight pathobiologic va riables, that is histologic grade, necrosis, lymphoid infiltration, number of mitoses, c-erbB-2 overexpression, p53, progesterone receptor, and bcl2 e xpression. An index for each tumor calculated on the basis of these eight f actors served to distinguish two different tumor phenotypes, designated A a nd B. Phenotype A is represented by tumors sharing most of the biologic fea tures of normal breast tissues: indeed, these tumors are characterized by a relatively high degree of differentiation, low proliferation, no necrosis or leukocyte infiltration, and no gene alterations. By contrast, phenotype B is quite divergent from the normal tissue because of its poor differentia tion, high proliferation, frequent gene alterations and evidence of a host immune reaction. As regards the disease progression, these two subsets show ed marked differences: phenotype A tumors had a low recurrence rate per yea r that remained constant over time and affected more frequently elderly pat ients, whereas group B tumors showed high aggressivity in the first years a fter surgery followed by a low long-term recurrence rate and were more freq uently seen in younger patients. These data suggest that breast carcinoma c onsists of two different subsets that can be identified on the basis of pat hobiologic features.