Yoshimura Fumihiro, Yoshida Yoichiro, Yamada Teppei, Tanaka Keita, Hayashi Takaomi, Shimaoka Hideki, Sakamoto Ryohei, Aisu Naoya, Yoshimatsu Gumpei, Hasegawa Suguru
Department of Gastroenterological Surgery, Fukuoka University Faculty of Medicine, Fukuoka, Japan.
Department of Medical Informatics and Digital Medicine, Fukuoka University Hospital, Fukuoka, Japan.
Cancer Rep (Hoboken). 2025 Jul;8(7):e70292. doi: 10.1002/cnr2.70292.
Early prediction of metastatic risk after tumor resection for colorectal cancer (CRC) is critical to improve treatment outcomes. Although circulating tumor DNA (ctDNA) is an important biomarker in CRC patients, positivity is variable because cutoff values for each gene have not been clearly established. When examining the mutant allele frequency (MAF) of a gene, the cutoff value is the same for the same gene, even if the mutation sites are different. In this study, we examined the relationship between MAF and the genetic mutation site and factors that influence the prediction of recurrence by ctDNA.
This study included 422 CRC patients who underwent surgery. ctDNA was sampled from blood samples of 102 CRC patients with KRAS, NRAS, and BRAF mutations and analyzed using the digital polymerase chain reaction system. Preoperative, postoperative day 1, postoperative day 7, and postoperative day 30 MAF were examined for each gene mutation site.
Kruskal-Wallis test revealed significant differences in MAF between mutated codon sites at all MAF assessment times (p < 0.001). The MAF values of KRAS codon 146 at all time points were significantly higher than for the other mutation sites. Steel-Dwass tests revealed KRAS codon 146 had significantly higher MAF values than KRAS codons 12 and 13 on all blood collection dates. Similarly, BRAF codon 600 had significantly higher MAF values than KRAS codon 12 on all blood collection dates.
This study revealed that MAF values differed significantly depending on the site of mutation, even for the same gene. These results suggest that MAF cutoff values may need to be established for each gene mutation site.
结直肠癌（CRC）肿瘤切除术后转移风险的早期预测对于改善治疗效果至关重要。虽然循环肿瘤DNA（ctDNA）是CRC患者的重要生物标志物，但由于每个基因的临界值尚未明确确定，其阳性率存在差异。在检测基因的突变等位基因频率（MAF）时，即使突变位点不同，同一基因的临界值也是相同的。在本研究中，我们研究了MAF与基因突变位点之间的关系以及影响ctDNA复发预测的因素。
本研究纳入了422例行手术的CRC患者。从102例KRAS、NRAS和BRAF基因突变的CRC患者的血样中采集ctDNA，并使用数字聚合酶链反应系统进行分析。对每个基因突变位点的术前、术后第1天、术后第7天和术后第30天的MAF进行检测。
Kruskal-Wallis检验显示，在所有MAF评估时间点，突变密码子位点之间的MAF存在显著差异（p < 0.001）。所有时间点KRAS密码子146的MAF值均显著高于其他突变位点。Steel-Dwass检验显示，在所有采血日期，KRAS密码子146的MAF值均显著高于KRAS密码子12和13。同样，在所有采血日期，BRAF密码子600的MAF值均显著高于KRAS密码子12。
本研究表明，即使是同一基因，MAF值也因突变位点的不同而存在显著差异。这些结果表明，可能需要为每个基因突变位点确定MAF临界值。
