Clinicopathologic significance of HER2 expression in gastric cancer: A retrospective study in Indian population.

Abstract

e15143 Background: Gastric cancer is the second most common cause of cancer related death worldwide. HER2 expression is an important biomarker for identifying patients who could respond to targeted therapy. The purpose of this study was to evaluate the frequency of HER2 expression and its clinicopathological significance in Indian population with gastric cancer. Methods: In this retrospective study, clinicopathological details and formalin fixed embedded tissue from patients with gastric and gastro-esophageal junction Adenocarcinoma of all stages from August 2009 to January 2012 were collected. HER2 status in the tissue was evaluated by the validated methods. IHC (Immunohistochemistry) scores of 3+ were considered positive, 2+ equivocal, 1+ and 0 negative for HER2. Equivocal staining was further evaluated with FISH (Fluorescence In-situ Hybridization) testing. The significance of HER2 expression was correlated with epidemiological, clinical, pathological and biochemical parameters using Pearson’s test. Progression free survivals (PFS) were compared using Log Rank test (Mantel-Cox). Kaplan-Meier curves were determined for PFS. SPSS version 17.0 was used for statistical analysis. Results: We studied 135 patients, of which IHC for HER2 was 3+ in 8.8%, 2+ in 10.4%, 1+ in 8.9% and zero in 71.9%. Among HER2 equivocal samples (n=14), FISH showed HER2 gene amplification in 14.2%. HER2 status was negative in 89.6% and positive in 10.4%.HER2 status significantly correlated with stage (p=0.03), smoking status (p=0.022) and not correlated with Age, Gender, Site, Lauren’s classification, Albumin, Hemoglobin. HER2 negative patients have better PFS (13.1 versus 7.1 months; p=0.005) and the levels of HER2 expression significantly influenced the PFS (p=0.006).Median PFS in patients with 3+, 2+, 1+ and zero IHC scores were 8.2, 8.8, 9.3, and 14.2 months respectively. Conclusions: The frequency of HER2 expression in gastric cancer in Indian population is comparable to the published data. HER2 in Gastric cancer serves as a prognostic marker.