OBJECTIVETo investigate the expression of miR-34a in stage II-III colorectal cancer and to elucidate its association with recurrence after radical resection.

METHODSmiR-34a expression level was detected in colorectal cancer patients with recurrence (40 cases) and without recurrence (40 cases) within 3 years after radical operation by real-time RT-PCR.

RESULTSNo association was observed between miR-34a and gender, age, location, local invasion, lymph node metastasis, cancer embolus, or tissue differentiation (all P>0.05). The expression level of miR-34a was lower in patients with recurrence compared to those without recurrence after radical surgery (P=0.039). Univariate analysis indicated that the median disease-free surviva l(DFS) of patients with low expression of miR-34a was worse as compared to those with high miR-34a expression (13.4 vs. 18.4 months, P=0.010), especially for stage III (P=0.003). In the recurrence group, the median DFS of patients with low miR-34a expression (n=14) was 13.4 months, which was shorter than that of patients with high miR-34a expression (n=26, 18.4 months, P=0.037). Multivariate analysis showed that miR-34a expression was an independent factor for colorectal cancer recurrence (RR=0.397, 95%CI:0.205-0.768, P=0.006).

CONCLUSIONThe down-regulated expression of miR-34a in colorectal cancer patients is associated with recurrence after radical operation. miR-34a may be a marker to predict tumor recurrence and metastasis of colorectal carcinoma.