Prognostic significance of HER2 expression based on trastuzumab for gastric cancer (ToGA) criteria in gastric cancer: an updated meta-analysis

The prognostic significance of HER2 expression in patients with gastric cancer remains controversial, partially due to the significant heterogeneity of the approaches and criteria used for HER2 assessment among different studies. We therefore conducted a meta-analysis enrolling only studies defining HER2 status by trastuzumab for gastric cancer (ToGA) criteria. Published studies investigating the association between HER2 expression and survival were identified. Only publications that defined HER2 expression using ToGA criteria were enrolled. Meta-analyses were performed by Revman 5.2. Pooled hazard ratio (HR) and its 95 % confidence interval (CI) were calculated to evaluate the risk of disease. A total of 11 studies were enrolled in meta-analyses. Pooled data of nine studies using univariate analysis showed that HER2 expression is not associated with overall survival (OS; pooled HR, 0.97; 95 % CI, 0.84–1.12; P = 0.63), which are maintained in six studies of multivariate analysis (pooled HR, 1.01; 95 % CI, 0.75–1.35; P = 0.95). The Q statistic test for nine studies of univariate analysis and for six studies of multivariate analysis showed no and low heterogeneity (I 2 = 22 % and P = 0.25; I 2 = 41 % and P = 0.13, respectively). Furthermore, pooled data of four studies without heterogeneity (I 2 = 0 %, P = 0.74) showed that HER2 expression were not associated with relapse-free survival as well, with a pooled HR of 1.08 (95 % CI, 0.84–1.37; P = 0.55) in patients with HER2 expression. In conclusion, this meta-analysis indicated that HER2 expression based on ToGA criteria is not related to the survival in patients with gastric cancer.