Prognostic role of the let-7 family in various carcinomas: A meta-analysis update.

PURPOSE: The role of let-7 family members in cancer prognosis has been the subject of increasing interest; however, the correlation between let-7 expression and cancer prognosis remains unknown. The goal of this study was to investigate the prognostic role of let-7 expression by performing a meta-analysis update of 31 studies.

METHODS: All relevant studies were searched on PubMed and Web of Science. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated, and subgroup analysis was performed for overall survival (OS) and disease-free survival (DFS) to evaluate the relationship between high let-7 expression and cancer prognosis. Heterogeneity and publication bias were also investigated.

RESULTS: We discovered that high let-7 expression can predict a better OS (pooled HR=0.69, 95% CI 0.60-0.80, transformed from lnHR and its 95% CI) and DFS (pooled HR=0.72, 95% CI 0.54-0.96, transformed from lnHR and its 95% CI) in various carcinomas, especially in digestive cancer. Subgroup analysis showed that high let-7 expression was significantly associated with a better DFS in Asians (pooled HR=0.50, 95% CI 0.39-0.64, transformed from lnHR and its 95% CI).

CONCLUSIONS: This meta-analysis showed that high let-7 expression is a prognostic factor for better OS and DFS in cancer patients, with particularly better DFS among the Asian populations. These results suggest that clinicians should treat patients with low let-7 expression more carefully. Future studies in large-scale populations among different ethnicities and regions are needed to definitively determine if let-7 expression can be used as a predicative biomarker for clinical assessment.