Performance of circulating methylated Septin9 gene DNA in diagnosis and recurrence monitoring of colorectal cancer in Western China

Methylated Septin9 (mSEPT9) has been suggested for CRC detection. To assess the performance of mSEPT9 in Western China, we compared its diagnostic and recurrence monitoring values with fecal occult blood test (FOBT), carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9).Overall 300 subjects including 209 CRC patients and 91 healthy subjects, who have performed mSEPT9, FOBT, CEA and CA19-9 tests, were involved. Sensitivity, specificity, and area under the ROC curve (AUC) were used to evaluate the efficacy of each method.Plasma mSEPT9 demonstrated an AUC of 0.860, and a sensitivity of 76.4 % for CRC detection. The sensitivity of mSEPT9 was higher than FOBT, CEA and CA 19-9. Though mSEPT9 presented a larger or equal sensitivity for stage Ⅱ-IV CRCs, FOBT showed a better sensitivity for stage I CRCs. Logistical analysis showed the ones with positive mSEPT9, FOBT and CEA were more likely to have CRC (all P < 0.01). Then, the three biomarkers built the nomogram predicting the probability of having CRC. The sensitivity of mSEPT9 was also much higher than CEA for CRC recurrence monitoring.The mSEPT9 test performed better than traditional tests for CRC detection, and should be recommended for FOBT-positive ones or individuals who refuse FOBT.