Histopathological Study of Gastric Adenocarcinoma with Special Reference to Expression of HER2/neu and Ki-67 Assessed by Immunohistochemistry

Introduction Gastric cancer has become the third leading cause of cancer deaths globally. It accounts for 5.7% of cancer around the world, with a rate of mortality around 8.2%. Evaluation of human epidermal growth factor receptor 2 (HER2)/neu overexpression for targeted therapies is presently the mainstay of treatment in gastric cancer. High Ki-67 index expression in gastric cancer is an indicator of poor prognosis. Objectives To study the prevalence of HER2/neu expression and Ki-67 index in various types, sites, grade, and stage of gastric adenocarcinoma and to determine the correlation between HER2/neu expression and Ki-67 index. Materials and Methods This is a prospective study in a tertiary care hospital, Kolkata from January 2019 to June 2020. Gastrectomy and endoscopic biopsy of gastric adenocarcinoma were studied for histopathology and immunohistochemistry (HER2/neu and Ki-67 index). Statistical analysis used: SPSS (version 21.0, IBM, Chicago, Illinois, United States) for windows software. Results Among 54 cases, most of them were intestinal type, antral, moderately differentiated, stage III cases. HER2 expression and high Ki-67 index were observed in 28.0 and 40.75% cases, respectively. Statistically significant correlation was found in both HER2 expression and high Ki-67 index with location of the tumor and pathological nodal (pN) stage. A positive correlation was found between HER2/neu score and Ki-67 index (p = 0.007) (correlation coefficient = 0.4). Conclusion A positive correlation was found between HER2/neu positivity and high Ki-67 index, both were associated with higher pathological tumor stage and pN stage. So, advanced cases may be considered for targeted therapy using trastuzumab.