BACKGROUND: MicroRNAs (miRNAs) are a class of endogenous small non-coding RNAs 
that have been shown to be aberrantly expressed in many human carcinomas. Of 
these miRNAs, miR-21 appears to be important in tumorigenesis given its 
up-regulation in almost all types of human cancer examined. However, its 
association with the clinicopathological features of human gastric cancer has 
yet to be addressed.
PATIENTS AND METHODS: Cancer tissues and corresponding normal tissues from 37 
patients with gastric cancer were examined for the expression level of miR-21 
using quantitative PCR and the clinical relevance of miR-21 was statistically 
analyzed.
RESULTS: miR-21 was overexpressed in 92% (34/37) of the gastric cancer samples 
examined. However, the patients with higher miR-21 expression did not have a 
worse prognosis.
CONCLUSION: miR-21 could serve as an efficient diagnostic marker for gastric 
cancer, but does not affect the clinical prognosis of gastric cancer patients.