The association among HER2, MET and FOXP3 expression and tumor regression grading in gastric adenocarcinoma.

Although the introduction of the perioperative chemotherapy on the management of gastric cancer has improved patients survival, heterogeneity of clinical outcomes has been evidenced in parallel to different histopathological regression pattern of gastric cancer cells. Thus, this study evaluated the tumor regression grading (TRG) in a series of post-treatment gastric tumors and its associations with HER2, MET, and FOXP3 expression. Material of 54 gastric cancer samples was available for TRG evaluation and immunohistochemistry. We found that total and subtotal pathologic response were significantly associated to the intestinal subtype (p = 0.04) and that well-differentiated tumors were significantly correlated with total or partial response (p = 0.019). Although not associated with the TRG, FOXP3 expression in gastric tumors was associated to poorly differentiated tumors (p = 0.03), to the diffuse and mixed subtypes together (p = 0.04) and to the presence of vascular infiltration (p = 0.04), while HER2 overexpression was associated to better differentiated cases (p = 0.04) and to the absence of vascular infiltration (p = 0.02). MET expression, however, showed no association with the analyzed clinicopathological factors. This study highlights the role of tissue differentiation on pathological response to neoadjuvant chemotherapy in gastric cancer and shows no impact between FOXP3, HER2 and MET expression in terms of TRG.