Abstract

Background: Breast carcinoma is not a homogenous disease. It is divided into 5 pathological subtypes of luminal1, luminal2, strongly Her2 positive, basal like, and normal breast like. Basal like breast carcinoma that accounts for about 15% of all breast cancers has an aggressive clinical behavior with the features of high nuclear grade, negative estrogen receptor, progesterone receptor, and Her2 reactivity (triple negative). Objectives: We aimed at identifying the prevalence of basaloid phenotype among triple negative (TN) cases in our region via immunohistochemistry (IHC) staining using basaloid markers. Methods: We reviewed breast cancer patients in Omid and Imam Reza hospitals, Mashhad, Iran, between 2003 and 2007. We obtained the paraffin blocks from TN cases for immune-staining using cytokeratin 5/6 (CK5/6), cytokeratin 14 (CK14) and epidermal growth factor receptor1 (EGFR1) markers. Results: The incidence of TN diseaseamongbreast cancers was 21% (156/747). Based on IHC reactivity with at least one of the basaloid markers, from 59 available samples, 44 (75.4%) were basaloid. Conclusions: In our region, most triple negative tumors were basal like breast cancer (BLBC). Among these cases, most immunereactivity was observed for EGFR1, followed by CK14 and CK5/6.

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