Somatostatin Receptor Subtype 2 A (SSTR2A) and HER2 Expression in Gastric Adenocarcinoma

Background: A possible anticancer role for somatostatin has been suggested. This study assessed the presence of somatostatin receptor subtype 2A (SSTR2A) in gastric cancer, correlating its expression with histological type, grade, human epidermal growth factor receptor 2 (HER2) expression, and disease outcome. Materials and Methods: Gastric cancer tissues of 51 consecutive patients were collected for immunohistochemical assessment of both SSTR2A and HER2 expression. Results: SSTR2A expression was observed in 38 (74.5%) cases. Prevalence of SSTR2A expression was significantly higher in well to moderately (GI-2) differentiated gastric cancer as compared to poorly (G3) differentiated tumors (96% vs. 52%; p<0.0.1), as well as in intestinal- than in diffuse-type cancer (97% vs. 20%; p<0.001). HER2 expression was positive in 18 (35%) patients, and it was associated with SSTR2A expression (r=0.50, p<0.001), being co-expressed in 17 (95%) out of 18 positive cases. RFS was significantly lower in patients with diffuse HER2 expression. Conclusion: This study demonstrated a co-localization between SSTR2A and HER2, potentially opening new therapeutic strategies for patients with gastric cancer.