Publication:

Study of HER-2/neu status in adenocarcinoma of stomach and gastroesophageal junction

Background To study the expression of Human epidermal growth factor receptor 2 (HER-2/neu) in adenocarcinoma of stomach and gastroesophageal junction and to study and describe the association of HER-2/neu expression with various clinicopathological parameters in Indian population.

Methods Immunohistochemical testing was done on 91 cases diagnosed as adenocarcinoma of gastric and gastroesophageal junction by histological examination to determine HER2 status. HER2 amplification was confirmed by fluorescence in situ hybridization (FISH) on cases that had equivocal (immunohistochemistry-IHC score 2+) HER2 expression. The association between HER-2 positivity and clinicopathological parameters was assessed by Chi-square test.

Results The HER-2 IHC results are as follows: score 3+ (positive): 8.79%; score 2+ (equivocal): 10.99%; score 0 and 1+ (negative): 80.22%. Of the 10 cases of equivocal IHC results, 2 cases (20%) showed amplification of HER-2 gene demonstrated by dual probe FISH analysis. The overall prevalence of HER-2 positivity detected using immunohistochemistry and FISH was 10.99% (10/91 cases). HER-2 positivity correlated with the tumor grade (well and moderately differentiated tumor, p=0.013) and intestinal type (p=0.025) but not with age, gender, pathological stage and lymph node metastasis.

Conclusions HER-2 positivity in our study was 10.99%. HER-2 positivity significantly correlated with intestinal type of adenocarcinoma and the grade of the tumor. Two cases with strong HER-2 staining but in less than 10% of the tumor showed gene amplification by FISH.