Letter regarding "MT1-MMP is not a good prognosticator of cancer survival: evidence from 11 studies" by Wu KP et al

With great interest, we carefully read a meta-analysis entitled "MT1-MMP is not a good prognosticator of cancer survival: evidence from 11 studies" in Tumor Biology (by Wu KP et al.), in which the investigators aimed to assess the association between MT1-MMP expression and prognosis of patients with various types of cancers by calculating the pooled hazard ratio (HR) with corresponding 95 % confidence interval (95 % CI). They have reached an important conclusion that MT1-MMP overexpression indicated an unfavorable overall survival (OS) in cancers and the pooled HR (95 % CI) was 2.46 (95 % CI 1.75-3.47). In addition, subgroup analysis showed the HRs (95 % CI) were 3.73 (95 % CI 2.67-5.21) and 2.46 (95 % CI 1.69-3.59) for MT1-MMP in lung cancer and gastric cancer, respectively. Before these results can be accepted, we would like to address several concerns related to this meta-analysis.