Objectives. To confirm that patients affected by colorectal cancer have the V2 region of Septin 9 (SEPT9) gene hypermethylated in the circulating free DNA from a peripheral blood sample before surgery and to determine if this hypermethylated DNA disappears from the patients after complete resection of the tumour. Methods. Plasma from 10 patients with colorectal cancer was collected preoperative and three months after surgery. The analysis of the methylation status of the promoter region of the SEPT9 gene was performed using a 7500 Fast Real-Time PCR System. Results. Hypermethylation of SEPT9 gene was detected in 8 out of 10 preoperative samples (one negative result was probed to be a Lynch syndrome) and in 4 out of 10 postoperative samples matching with the cases of recurrence or persistence of disease. This means that, in this sample, the preoperative sensitivity and specificity of the test were 88.9% and 100%, respectively, and there is 100% correlation between the positive results of the SEPT9 test and a recurrence/persistence of the disease in patients after surgical resection. Conclusions. Our study shows that circulating hypermethylated SEPT9 is a specific colorectal cancer biomarker. This hypermethylated SEPT9 DNA disappears around three months after surgery and that circulating hypermethylated SEPT9 may be the first noninvasive marker for postsurgical diagnosis; this conclusion must be confirmed with a more significant number of patients.

中文翻译：

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通过甲基化 Septin 9 基因的液体活检获得结直肠癌治愈性手术生物标志物的第一步。

目标。确认受结直肠癌影响的患者在手术前外周血样本的循环游离 DNA 中的 Septin 9 ( SEPT9 ) 基因的 V2 区域高甲基化，并确定这种高甲基化 DNA 在完全切除肿瘤后是否从患者身上消失。方法。术前和术后 3 个月收集了 10 例结直肠癌患者的血浆。使用 7500 快速实时 PCR 系统对SEPT9基因的启动子区域的甲基化状态进行分析。结果。SEPT9的高甲基化10个术前样本中有8个（1个阴性结果被探测为Lynch综合征）和10个术后样本中有4个与疾病复发或持续存在的病例相匹配。这意味着，在该样本中，该测试的术前敏感性和特异性分别为 88.9% 和 100%，并且SEPT9测试的阳性结果与术后患者的疾病复发/持续存在 100% 的相关性。手术切除。结论。我们的研究表明，循环中的高甲基化SEPT9是一种特定的结直肠癌生物标志物。这种高甲基化的SEPT9 DNA 在手术后三个月左右消失，而循环中的高甲基化SEPT9可能是术后诊断的第一个非侵入性标志物；这一结论必须得到更多患者的证实。