Immunohistochemical Expression of Human Epidermal Growth Factor Receptor 2 (HER2) and p53 in Gastric Adenocarcinoma: A Pilot Study from Northern India.

Introduction: After the recent approval of Trastuzumab (anti-HER2 antibody) for the treatment of HER2 overexpressed Gastric Adenocarcinoma (GA), importance of HER2 testing is increasingly recognized. However, there is paucity of studies for HER2 overexpression in the Indian patients of GA. Similarly, study of p53 expression in the Indian patients of GA is infrequent.

Aim: To study immunohistochemical expression of HER2 and p53 in GA biopsy samples.

Materials And Methods: This was a cross-sectional observational study. The expression of HER2 and p53 by immunohistochemistry were analyzed in 50 cases of GA. The HER2 expression was scored as negative (0 and 1+), equivocal (2+), and overexpression (3+). The p53 expression was quantified as negative (0-9% tumour cells) and positive (≥10% tumour cells). The intensity of p53 expression was assessed as strong and weak.

Results: Mean age of the patients was 56.8±14.8 years. Male:female ratio was 2:1. Histological types of adenocarcinoma were intestinal (68%), diffuse (28%), and indeterminate (4%). HER2 overexpression and equivocal results were present in 10% cases, each. Overall, a positive expression of p53 was seen in 72% (strong and weak intensities: 66.7% and 33.3% cases, respectively).

Conclusion: As compared to HER2 overexpression, a higher incidence of p53 expression was seen (10% vs.72%) in GA.