Background and Aim: Breast cancer (BC) is the most common type of cancer among Iranian women and affects them around a decade sooner compared with developed countries. Human epidermal growth factor receptor type ۲ (HER۲) plays an ultimate role in triggering of BC. However, the prognostic relevance to BC patients of the other HER family members has been a controversial matter among the scientists. This study was conducted to evaluate the usability of multiplex ligation-dependent probe amplification (MLPA) technique for copy number determination of HER gene family members in invasive ductal BC and to explore the association of
HER۱-۴ genes with clinicopathological characteristics of BC patients.Methods: Clinical and immunohistochemical factors were assessed in ۱۰۴ BC patients and the molecular subtype of each tumor sample was also determined. Furthermore, HER-۲/neu status was assessed by immunohistochemistry (IHC) and equivocal results were confirmed by Fluorescent in situ hybridization (FISH). The copy numbers of ERBB۱-۴ genes were determined by MLPA.Results: ۱۴.۴% of cases showed HER-۲/neu over expression at the protein level assessed by IHC method whereas ۲۵% of all cases showed HER۲ gene-amplification by MLPA. Moreover, only ۲.۸%and ۱.۹% of cases showed amplification in HER۱ and HER۴ genes, respectively. We did not observe any copy number alterations in HER۳ gene. Behind that, HER۱/HER۲ and HER۴/HER۲ co-amplification was occurred in ۱.۹% and ۰.۹% of cases, respectively. Our results indicated a significant association between HER۲ copy numbers and histological grade (p value= ۰.۰۱), stage (p value= ۰.۰۲), and tumor subtypes (p value= <۰.۰۰۱). In addition, we found
MLPA method more accurate (specificity= ۸۲%) compared to IHC technique (specificity= ۷۷.۶%) in advanced tumor stages (۳A, ۳B, and۴).Conclusion: Based on our findings
MLPA technique is a fast, precise and low-cost technique to detect HER۲ copy number alterations especially in advanced tumor stages and because of infrequent amplification that we found in HER۱ and HER۴ and also, the lack of amplification in HER۳, their clinical significance in the prognostic evaluation of BC patients remained mainly obscure.