ABSTRACT
Purpose@#Circulating cell-free single-stranded DNA (ccf-ssDNA) is extracellular DNA and it is a useful biomarker for the diagnosis of tumors and predicting the prognosis of tumors. However, the clinical usefulness of ccf-ssDNA in colorectal cancer (CRC) is not well known. Thus, the purpose of this study was to investigate the clinical usefulness of ccf-ssDNA in CRC. @*Methods@#The study was conducted on 44 patients who had undergone surgery for CRC, and ccf-ssDNA level was measured before surgery and statistical analysis was performed on clinical factors. @*Results@#The association between ccf-ssDNA level and clinicopathological factors was analyzed and compared, and these factors included age, sex, body mass index, diabetes mellitus, hypertension, tumor markers (carcinoembryonic antigen and carbohydrate antigen 19-9), tumor location, size, stage (TNM), recurrence, and death. The group with a ccf-ssDNA level of ≥ 7.5 ng/μL had a lower age (P = 0.010), and was associated with diabetes mellitus (P = 0.037) and lymph node metastasis (P = 0.049). Multivariate analysis of disease-free survival showed that lymph node metastasis and ccf-ssDNA level (hazard ratio, 10.011; 95% confidence interval, 2.269–44.175; P = 0.002) were independent prognostic factors for recurrence. In terms of overall survival, there were no statistically significant results except for vascular invasion. @*Conclusion@#This study showed that ccf-ssDNA level in plasma in CRC patients was an independent prognostic factor that could predict recurrence non-invasively. In this regard, further evaluation with a prospective, large sample size study will be needed to obtain additional results.