Low, intermediate and high grade breast carcinomas as determined by histotyping, immunohistochemical prognosticators...

Low grade breast cancers i.e. mucinous (17 cases--3.2%), tubular (7 cases--1.3%) and invasive cribriform carcinomas (3 cases--0.5%) have been identified within a series of 524 breast cancers only by histotyping in hematoxylin-eosin stained sections: the reactivities of immunohistochemical prognosticators as estrogen/progesterone receptors (ER, PgR), growth fraction (GF: Ki67), p53 and c-erbB-2 oncoproteins are in agreement with clinical behaviours. Invasive papillary carcinomas (9 cases--1.6%) are not to be considered low grade carcinomas. Intermediate grade cancers are also determined by histotyping. Medullary carcinoma (13 cases--3.4%) has a paradoxical behaviour displaying a favourable clinical prognosis together with high grading and GF, absence of ER, PgR, high p53 and c-erbB-2 values, as compared with invasive ductal carcinomas: an extensive tissue immune response as suggested by a heavy lymphocyte infiltration may explain this behaviour. Invasive lobular carcinoma (62--11.6%) shows an intermediate immunohistochemical pattern, paralleling an intermediate prognosis, when compared with low and high grade carcinomas: ER, PgR and GF positivities are nearly the same as in ductal carcinomas whereas grading, p53 and c-erbB-2 are less expressed. These data are confirmed both for lobular carcinomas as a whole and for all variants of this kind of tumors. Invasive ductal carcinomas (413 cases--79%) may be stratified on three prognostic classes corresponding to histological grading (G1, G2, G3). Significant relationships of grading with all the immunohistochemical prognosticators studied has been observed. It may be concluded that grading is a parameter of paramount importance in this group of tumors.