OBJECTIVETo investigate the relationship between methylation status of APC gene in both peripheral blood and tumor tissues and clinical-pathology characteristics in patients with esophageal squamous cell carcinoma(ESCC), and to study the dynamic change of APC methylation in peripheral blood in the perioperative period.

METHODSReal-time MSP technique was used to detect methylation status of APC in tumor tissues, adjacent normal tissues and peripheral blood on the day before the surgery, intraoperative, postoperative day 7 in 76 cases with ESCC. Sixty healthy volunteers matched by age and gender were randomly selected as controls.

RESULTSThe methylation rate of APC in tumor tissue and peripheral blood was 44.74%(34/76) and 42.11%(32/76), respectively, which were significantly higher than that in adjacent normal tissue and controls [6.58%(5/76) and 1.67%(1/60), P=0.000]. The methylation rates showed good agreement between tumor tissues and peripheral blood, which could be verified by ROC curve(A Zeta=0.849, P=0.000). APC methylation rate was significantly related to pathological staging, lymph node metastasis, depth of invasion, and invasion of nerve and vessel (P<0.05). The results demonstrated that family history of cancer was independently associated with APC methylation in peripheral blood(P<0.05). DNA methylation rates in peripheral blood showed an initial increase and then decreased in the preoperative period, intraoperative and postoperative.

CONCLUSIONThe methylation rates of APC among free DNA in peripheral blood in patients with ESCC reflect tumor progression, and decrease with the solid tumour resection.