To investigate the predictive value of serum exocrine miR-224 for recurrence of patients with liver metastasis from colorectal cancer (CRC) after radio-frequency ablation (RFA).

The difference of miR-224 expression between CRC tissues and normal tissues was analyzed based on TCGA data set. From October 2014 to March 2020, ninety patients with liver metastasis from CRC who underwent RFA treatment in Mianyang Hospital, School of Medicine, University of Electronic Science and Technology of China were selected as the study group, and eighty-seven patients with non-metastatic CRC as the control group. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression level of serum exocrine miR-224. After RFA, the patients were followed up regularly and recorded their recurrence.

TCGA data set showed that miR-224 was overexpressed in CRC tissues (P<0.001) and was associated with shorter overall survival in CRC patients (P=0.013). In the clinical validation test, compared with the control group, the expression level of serum exocrine miR-224 in the study group was significantly increased [1.63 (0.97, 2.73) vs. 1.06 (0.71, 1.32), Z=-5.134, P<0.001]. The area under receiver operating characteristic curve (AUC) of serum exocrine miR-224 to distinguish between liver metastatic and non-metastatic CRC was 0.723 (95% CI: 0.645-0.802). The median follow-up was 7.5 months (range 1-42 months), and the 3-year recurrence-free survival (RFS) rate was 34.4% (31/90). Compared with the non-recurrence group, the expression level of serum exocrine miR-224 in the recurrence group before treatment was significantly increased [2.14 (1.44-3.11) vs. 0.81 (0.51-1.70), Z=-4.191, P<0.001], and the AUC of serum exocrine miR-224 in predicting tumor recurrence was 0.770 (95% CI: 0.663-0.877). After further multivariate analysis, serum exocrine miR-224 was an independent prognostic factor for RFS in patients with liver metastatic from CRC (OR=1.820, 95% CI: 1.070-3.096, P=0.027).

Serum exocrine miR-224 has a certain predictive value for recurrence and prognosis in patients with liver metastasis from CRC after RFA, which can provide a certain reference for the selection of clinical treatment decision.