Blood-Based Screening to Combat the Rise of Colorectal Cancer in China?

Colorectal cancer (CRC) is a major cause of morbidity and mortality throughout the world, accounting for over 9% of all cancer incidence. In developed countries, the incidence and mortality rates of CRC have dropped significantly in the last twenty years, while these rates in developing countries (such as China) have increased significantly. While lifestyle and dietary changes in developing countries have contributed to the increase in CRC incidence, such apparent discordant trends are largely attributable to the differential screening programs.

CRC is ideally positioned for screening, particularly non-invasive blood or stool-based screening. Firstly, CRC often develops over a long period of time, providing an ample time window for detection. Secondly, accurate diagnostic and therapeutic colonoscopies are available as a follow-up for positive screening results. Detecting CRC at an early stage is likely to benefit patients given the much better prognosis.

In developing countries, the shortage of competent physicians is severe and it is unlikely to change in the foreseeable future. As such, standardized and cost-effective molecular tests may be the most practical way to combat CRC. As DNA methylation is an early event in carcinogenesis, we performed extensive DNA methylation biomarker discovery using prospectively collected clinical samples to identify about 10 markers with high specificity for CRC in plasma. A single-tube multiplex qPCR assay is subsequently developed to quantify tumor-derived methylation signals in plasma. In several independent cohorts, we demonstrated that the test may have sufficient specificity, sensitivity, and cost-effectiveness for nationwide population screening.