[Immunohistochemical characterisation of breast cancer: towards a new clasification?]

The aim of this paper is to determine the possible association between five different profiles of immunohistochemical expression related to clinical, histopathological and immunohistochemical known prognostic value variables for breast cancer.

A total of 194 breast carcinoma tumour samples were studied. In this study five groups or immunohistochemical profiles were defined, based on expression of hormone receptors (oestrogen or progesterone) and/or Her2/neu (luminal-type A, luminal-type B, mixed profile, Her2/neu profile and triple-negative-type profile) and we studied whether there are differences between them with regard to clinical, histopathological and immunohistochemical variables that have a known prognostic significance.

In the series we found 134 (69%) cases corresponding to a luminal immunophenotype, of which 98 (50.5%) were from the luminal A group and 36 (18.6%) from luminal B. Twenty-nine cases (15.9%) were triple-negative, 18 (9.3%) mixed and 13 (6.7%) Her2/neu type. It is worth noting the relationship between the triple-negative and Her2/neu immunophenotypes and the more poorly differentiated histological forms (62% and 60%, respectively) and between the luminal A group and well-differentiated tumours (p = 0.008). Expression of ki67 was high in the triple-negative group (73.9%) and low in the luminal A group (26.3%; p = 0.001). The expression of p53 was also greater for the Her2/neu (55.5%) and triple-negative (60.8%) groups (p = 0.0005) than for the others.

The subgroups without hormone receptor expression, with Her2/neu overexpression or without (triple-negative group), have characteristics associated with variables of a poorer prognosis. The lack of progesterone receptor expression also seems to be associated with these.