Expression of Novel Immunohistochemical Markers in Renal Cell Carcinoma, Unclassified

Abstract

Routine hormone receptor protein and human epidermal growth factor receptor 2 (HER2) oncoprotein analysis on invasive breast carcinomas provide therapeutic, predictive, and prognostic values and have revealed clinically significant subgroups. The best characterized of these have been designated luminal A, luminal B, HER2, and the so-called triple-negative tumors. The aim of this study was to determine the expression of basal cytokeratins and epidermal growth factor receptor (EGFR) in triple-negative invasive breast carcinomas in Puerto Rico. All invasive breast carcinoma cases consulted to our laboratory from 2008 to 2010, were included in this study. Assessment of the level of intratumoral expression of estrogen receptor, progesterone receptor, and HER2 was done. The cases were divided into cohorts based on their molecular categories and analyzed according to the histologic tumor grade and age. Triple-negative tumors were further analyzed according to their expression of EGFR and cytokeratins 5/6 and 14. From 717 breast consultation cases reviewed during the study period, 487 cases of invasive breast carcinoma were included in the study. The prevalence of molecular categories was 65%, 10%, 9%, and 15% for the luminal A, luminal B, HER2, and triple-negative groups, respectively. Assessment of basal cytokeratins and EGFR expression was performed on 41 triple-negative tumors, of which 71% expressed at least 1 basal cytokeratin or EGFR and 29% were negative to all markers. A statisticallly significant difference (P < .001) was found between the molecular categories and tumor histological grade. Triple-negative tumors were related to a higher grade. No statistical difference was found between the molecular categories and patient age. Prevalence and relation between tumor grade and molecular categories and the expression of basal cytokeratins in triple-negative tumors in our population is comparable to that published in the literature for other ethnic groups.