Survival advantage and clinicopathological significance of microRNA-22 in cancers: a meta-analysis

An increasing number of studies revealed that microRNA-22 as a biomarker may play a significant role in the cancer patients' prognosis, but the accurate prognosis value of microRNA-22 remains somewhat controversial. Thus, we comprehensively searched the database and performed this study to explicate the accurate value of microRNA-22 in the cancer patients' prognosis. This meta-analysis revealed that elevated expression of microRNA-22 correlated with good overall survival (OS) and disease-free survival (DFS)/progression-free survival (PFS)/recurrence-free survival (RFS) in cancers, while no significant association was found in metastasis-free survival (MFS)/distant metastasis-free survival (DMFS). Through the subgroup analysis for OS and DFS/PFS/RFS, we found that elevated expression of miR-22 significantly correlated with good prognosis in most subgroups, while it predicted a worse prognosis in nasopharyngeal carcinoma subgroup. And besides that, elevated expression of miR-22 was negatively correlated with TNM stage, lymph node metastasis, distant metastasis and recurrence, while no significant association was found between microRNA-22 expression and T stage, tumor differentiation, and lymphatic invasion. Our meta-analysis demonstrated that elevated expression of microRNA-22 predicted a good OS and DFS/PFS/RFS in cancer patients; meanwhile, its high expression also means earlier TNM stage, and lower likelihoods of lymph node metastasis, of distant metastasis and of recurrence. If we regularly monitor miR-22 expression in cancer patients, it might be useful for us to predict cancer prognosis in future clinical applications.