Prognostic role of Smad4 expression in gastric cancer: a meta-analysis

Smad4 is located on chromosome 18q21 and acts as a central mediator in TGF-beta superfamily signaling to inhibit relevant tumor development and progression. However, the prognostic role of Smad4 in gastric cancer (GC) was still controversial. Our aim of this meta-analysis was to evaluate the potential association between Smad4 expression and clinicopathological differences in GC patients. A total of 6 studies with 1021 GC patients up to April 2016 were included in this study. Our data demonstrated that Smad4 expression did related to the gender (pooled OR=0.812, 95% CI=0.381-1.732, P=0.591, random effect), Lauren histology (pooled OR=1.015, 95% CI=0.2214.659, P=0.985, random effect) and tumor differentiation (pooled OR=0.709, 95% CI=0.403-1.248, P=0.233, random effect) of GC patients. But reduced Smad4 was significantly associated with the lymph node metastases (pooled OR=0.580, 95% CI=0.339-0.990, P=0.046, random effect) and TNM stage (pooled OR=0.645, 95% CI=0.426-0.977, P=0.039, fixed effect), which finally led to a shorter overall survival (OS) rate (RR=0.388, 95% CI=0.168-0.895, P=0.026) in GC patients, compared to the preserved cases. These results strongly suggested that Smad4 might serve as a novel biomarker for prognostic indicator, and could be a potential therapy for diagnosis and treatment in GC.