Screening of Colorectal Cancer Using Improved SEPT9 (Septin 9) Gene Methylation Assay in Chinese Population

1. Background

Colorectal cancer (CRC) is the third most common malignancy of the gastrointestinal system. Regular screening, early detection and early treatment of colorectal cancer can achieve better prevention and even cure. Currently, 60%-70% of CRC patients are not diagnosed until late stages and only 11.8% of cases are detected at early stage. It is therefore urgent to reduce the CRC mortality by improving the early screening rate. In China,fecal occult blood test (FOBT) and colonoscopy are available presently for early CRC screening. FOBT is widely used due to its low cost and non-invasiveness, however, its false positive rate is relatively high due to many interfering factors. The more advance FOBT, fecal immunochemical test (FIT), has greatly improved the test specificity compared with the traditional chemical method and its compliance is high, but is still subject to the influence of other intestinal diseases, leading to low positive predictive value. In contrast, the compliance for colonoscopy is low due to its invasiveness, cost and risk of complications.

In recent years, the plasma-based SEPT9 gene methylation assay has proved to be a promising method for the early detection of CRC. Many clinical studies have demonstrated that the methylated SEPT9 gene is a useful biomarker for early CRC detection.At present, Epigenomics' Epi proColon 2.0 CE is the only commercialized assay of SEPT9 gene methylation globally. This product has obtained the approval from the European Union CE certification, the Chinese FDA and the Argentina FDA. It has completed key clinical data submission to the US FDA, with reasonable expectation of the US FDA approval soon. Services based on the SEPT9 gene methylation assay are also provided in clinical laboratories such as quest, Arup, companion to DX and gamma dynacare with the common medical procedure code (CPT code) 81401. In China, BioChain (Beijing) Science and Technology, Inc, a strong partner of Epigenomics AG, has developed its own SEPT9 gene methylation assay with the agreement of Epigenomics AG. 2. Estimation of sample size

Based on the equation N=Z2* (P (1-p))/E2 for known positivity detection rate, the investigators calculated the number of samples needed for the trial, in which N represents the sample size, Z is a statistical parameter (Z=1.96 for 95% confidence interval); E represents the error (5% was chosen in this study), and P represents the probability (putative positive detection rate). The investigators choose 0.75 for P value based on existing literatures on SEPT9 sensitivity. The number of CRC cases is calculated as 288 based on the equation above. The investigators aim to collect complete information for 300 cases due to information incompleteness and tracking loss. etc. Based on the estimation that CRC account for 30% of high-risk outpatients and inpatients in Chinese hospitals, the total number of patients in the trial should be no less than 1000 cases. The investigators aim at recruiting 1200 cases in this trial taking account of 20% loss of follow-up rate.

The final actual number of cases for this trial was 1031, due to loss of tracking, incomplete test or clinical data, or samples that did not meet the test criteria. 3. Subject grouping