Differences in HER2 over-expression between proximal and distal gastric cancers in the Chinese population.

AIM: To investigate HER2 expression and its correlation with clinicopathological variables between proximal and distal gastric cancers (GC) in the Chinese population. METHODS: Immunostaining of HER2 was performed and scored on a scale of 0-3 in 957 consecutive GC cases, according to the revised scoring criteria of HercepTestTM as used in the ToGA trial. Correlations between HER2 expression and clinicopathologic variables of proximal (n = 513) and distal (n = 444) GC were investigated. RESULTS: Our results showed that HER2 expression was significantly higher in the proximal than in distal GC (P < 0.05). Overall, HER2 expression was significantly higher in male patients (P < 0.01), the Lauren intestinal type (P < 0.001), low-grade (P < 0.001) and pM1 (P < 0.01) diseases, respectively. There was a significant difference in HER2 expression among some pTNM stages (P < 0.05). In contrast, HER2 expression in the distal GC was significantly higher in male patients (P < 0.001), low-grade histology (P < 0.001), the Lauren intestinal type（P < 0.001), and pM1 (P < 0.001). In the proximal GC, however, higher HER2 expression scores were observed only in tumors with low-grade histology (P < 0.001) and the Lauren intestinal type (P < 0.001). CONCLUSION: HER2 over-expression in GC of Chinese patients was significantly more common in proximal than in distal GC, and significantly correlated with the Lauren intestinal type and low-grade histology in both proximal and distal GC, and with pM1 disease and male gender in distal GC.