BACKGROUND: MicroRNAs (miRNAs), endogenous small non-coding RNAs, are stably 
detected in human plasma. Early diagnosis of gastric cancer (GC) is very 
important to improve the therapy effect and prolong the survival of patients. We 
aimed to identify whether four miRNAs (miR-223, miR-21, miR-218 and miR-25) 
closely associated with the tumorigenesis or metastasis of GC can serve as novel 
potential biomarkers for GC detection.
METHODOLOGY: We initially measured the plasma levels of the four miRNAs in 10 GC 
patients and 10 healthy control subjects by quantitative reverse transcription 
polymerase chain reaction (qRT-PCR), and then compared plasma miRNA results with 
the expressions in cancer tissues from eight GC patients. Finally, the presence 
of miR-223, miR-21 and miR-218 in the plasma was validated in 60 GC patients and 
60 healthy control subjects, and the areas under the receiver operating 
characteristic (ROC) curves of these miRNAs were analyzed.
RESULTS: We found that the plasma levels of miR-223 (P<0.001) and miR-21 
(P<0.001) were significantly higher in GC patients than in healthy controls, 
while miR-218 (P<0.001) was significantly lower. The ROC analyses yielded the 
AUC values of 0.9089 for miR-223, 0.7944 for miR-21 and 0.7432 for miR-218, and 
combined ROC analysis revealed the highest AUC value of 0.9531 in discriminating 
GC patients from healthy controls. Moreover, the plasma levels of miR-223 
(P<0.001) and miR-21 (P = 0.003) were significantly higher in GC patients with 
stage I than in healthy controls. Furthermore, the plasma levels of miR-223 were 
significantly higher in GC patients with helicobacter pylori (Hp) infection than 
those without (P = 0.014), and significantly higher in healthy control subjects 
with Hp infection than those without (P = 0.016).
CONCLUSIONS: Plasma miR-223, miR-21 and miR-218 are novel potential biomarkers 
for GC detection.