Liquid biopsy has a potential to predict the colorectal cancer patients with destiny for recurrence after curative surgery

Abstract

Background: Nowadays, detection of circulating cell-free tumor DNA (cfDNA) in serum is the frontier noninvasive approach. We reported the utility of detection of cancer-specific methylated CpGs from cfDNA for monitoring tumor dynamics during systemic chemotherapies in colorectal cancer (CRC) patients. The purpose of this study was to establish whether our assay can predict patients with risk for recurrence prospectively by analyzing blood obtained before curative surgery. Methods: Methylation status of CpG sites, considered as cancer-specific alteration, and concentration of cfDNA were evaluated from blood plasma obtained before surgical resection. To analyze aberrant cancer-specific methylation, we modified the highly sensitive assay for bisulfite DNA followed by fluorescence-based PCR, as reported previously (Nagasaka T. et al, Analysis of fecal DNA methylation to detect gastrointestinal neoplasia, J Natl Cancer Inst. 2009 Sep 16;101(18):1244-58. doi: 10.1093/jnci/djp265. Epub 2009 Aug 21). This can detect 8 loci of target promoters, therefore the methylation score (MS) could be ranged from 0 to 8 at a given time, and we also evaluated methylation density in a quantitative manner. Results: Of the 88 CRC patients enrolled, 16, 26, 25, and 21 patients were stage I, II, III, and IV, respectively. Therefore, to examine whether liquid biopsy can predict CRC patients with risk for recurrence, we focused on stage II and III patients. Of the 51 stage II and III patients, 5 patients received neoadjuvant therapies. Thus, a total of 46 stage II and III CRC patients were finally analyzed. Of the 46 CRC patients, during our observation period [median followup was 1056 days (range; 343-1401 days)], only three stage III patients experienced recurrences after curative surgery. Mean plasma MS of the patients with recurrence was increased compared with the patients without recurrences (1.11 vs. 0.8, not significant). When we assessed a methylation density, the mean plasma methylation density of the patients with recurrence was 16078 points (95%CI: 3074-29082) whereas that of the patients without recurrence was 6611 points (95%CI: 3704-9519, P = 0.16). Conclusions: Although the number of the patients who experienced recurrences after curative resection was too small, our circulating cell-free DNA-based assay showed a potential to predict CRC patients with risk for recurrence after curative surgery.