The significance of detection of ECAD gene methylation in combination with FOBT in stool in the diagnosis of colorectal cancer

HE Ying; HUANG Wei-zhen; OUYANG Kao-bin; YUAN Xia

doi:10.3969/j.issn.1001-9448.2016.23.016

Abstract：Objective To investigate the diagnostic value of detecting methylation level of ECAD in combination with fecal occult blood test (FOBT) in stool for colorectal cancer (CRC).Methods A total of 50 healthy people, 50 patients with colorectal benign lesion and 50 CRC patients were included in this study .The stool samples from these pa-tients were collected and ECAD gene methylation level was detected using methylation specific PCR ( MSP) .The clinical status and the pathological diagnosis of all patients were confirmed by colonoscopy .The sensitivity and specificity of ECAD and FOBT for the diagnosis of CRC were analyzed using statistic method .Results The positive rate of stool ECAD gene methylation in CRC patients was 78%, which was significantly higher than control groups (21%).Consistently, the posi-tive rate of FOBT in CRC patients was also significantly higher than control groups (64% vs.14%).Besides, ECAD methylation level in stool was significantly associated with tumor number ( P=0.048 ) , histological type ( P=0.006 ) , TNM stage (P=0.002), and lymph node metastasis (P=0.002).The sensitivity and specificity of stool FOBT methyla-tion for CRC diagnosis were 64%(95%CI:49.1-76.7%) and 86%(95%CI:77.3-91.9%), respectively.Where-as the sensitivity and specificity of ECAD were 78%(95%CI:63.7-88.0%) and 79%(95%CI:69.5-86.2%), re-spectively.The under-ROC curve area of ECAD was 0.795 (95%CI:0.716-0.874%), which was higher than that of FOBT (AUCROC:0.806, 95%CI:0.728-0.884%).More importantly, the area of combined detection of two factors reached 0.806 (95%CI:0.728-0.884%).Conclusion ECAD gene methylation in stool is an efficient method for ear-ly diagnosis for CRC patients .The combined detection of ECAD and FOBT in stool may increase the accuracy of diagnosis of CRC.