Diagnostic and prognostic role of steroidogenic factor 1 in adrenocortical carcinoma: a validation study focusing on clinical and pathologic correlates.

The pathologic characterization of adrenocortical cancer is still problematic for several reasons, including the identification of novel markers of diagnostic or prognostic relevance. Among them, steroidogenic factor 1 deserves major interest because of its potential usefulness as a marker of adrenocortical derivation and of biological aggressiveness. Our aim was to validate its prognostic relevance in a large series of adrenocortical cancer, comparing the performance of 2 different commercial antibodies and investigating its expression in adrenocortical cancer variants and in comparison with clinical and pathologic features. Seventy-five (including 53 classical, 10 myxoid, and 12 oncocytic) adrenocortical cancer cases were included in tissue microarrays and analyzed for the immunohistochemical expression of steroidogenic factor 1 using 2 commercial antibodies, 1 polyclonal and 1 monoclonal (N1665). Nuclear steroidogenic factor 1 staining was assessed using a semiquantitative score and correlated with adrenocortical cancer type and clinical pathologic characteristics. A weak but significant correlation was found comparing the 2 antibodies with a positive rate of 88% and 58% using the monoclonal and polyclonal antibodies, respectively. High steroidogenic factor 1 expression with the N1665 antibody was positively correlated with high mitotic count, high Ki-67 index, and high European Network for the Study of Adrenal Tumors (ENSAT) stage and negatively associated with loss of functionality and presence of oncocytic features. Moreover, high steroidogenic factor 1 expression with this same antibody was significantly associated at univariate analysis with a decreased survival, together with high Ki-67 and mitotic indexes, with a trend to significance confirmed by multivariate analysis, thus supporting the detection of steroidogenic factor 1 using the N1665 antibody as a novel prognostic marker in adrenocortical cancer.