Correlation analysis of gFOBT and SEPT9 in the same healthy samples showed specificity of 70.6% (12/17 negative) for gFOBT and 76.5% (13/17 negative) for CHIR99021 IC50 SEPT9. For CRC, all of the patients were SEPT9 positive (100%; 22/22) whereas only 68.2% (15/22) were positive by gFOBT. Compared to gFOBT, we found the CEA assay was more precise for detecting CRC, with 85.2% specificity, but was also less sensitive (51.8%). CEA is the most widely used serum tumor marker for CRC monitoring. This antigen is expressed on the surface of the colonic epithelial cells and in the case of malignancy, CEA is expressed on the whole cell surface and excreted at high levels into the bloodstream . Elevated preoperative CEA is associated with reduced survival after surgical resection of CRC.
Monitoring of CEA in the postoperative period can help to identify patients with metastasis, although its sensitivity for pulmonary metastasis is less than for hepatic metastasis . The primary use of CEA is in follow-up of CRC after surgical or chemotherapy treatment. In our study, only 51.8% (14/27) of CRC patients showed elevated CEA levels. From the comparison of CEA and Septin 9 in the same patients, the specificity of the CEA assay was 85.2% (23/27), higher than the Septin 9 specificity (70.4%; 19/27); however Septin 9 was much more sensitive (100%; 27/27) in cancer samples than CEA (51.8%; 14/27). Hence serum CEA is not as a reliable method for CRC screening as Septin 9 . Septins have been originally detected in cell division cycle mutant yeast, but recently it is become known that Septin proteins play role in several cellular functions.
They have been implicated in neoplasia, neurological and infectious diseases . Previous studies used the first generation Septin 9 detection kit (Epi proColon 1.0) and found Septin 9 positivity in 9% of healthy subjects and 73% of CRC patients �C. In our study, new generation Septin 9 blood test, the Epi proColon 2.0 was used. The advantages of Epi proColon 2.0 kit are fewer handling steps, shorter time to result and increased clinical performance compared to the first generation test . In the present study, we first analyzed the data using the high sensitivity (1/3 analysis method) as described previously . In the current study only 4 of the 92 (4.3%) CRC cases showed SEPT9 negativity, all of them stage I CRC, and the test had 95.
6% sensitivity for CRC. Its specificity (84.8%) was similar to that found for CEA (Table 3). Seventy-eight of the 92 (84.8%) healthy subjects were negative for Septin 9. Healthy subjects that were positive for Septin 9 did not show any sign of colonic disease at the GSK-3 time of colonoscopy. However, it remains to be seen whether they will develop any illness in the future. Septin 9 was sufficiently sensitive to detect early stage CRC as well. For stage I CRC, 95.6% were identified by Septin 9 methylation, and all of the stage II CRC samples showed positive test results.