Bowel cancer (also known as colorectal cancer or colon cancer) is the third most common cancer, and is responsible for over 16 000 deaths in the UK every year. The sooner bowel cancer is detected, the more easily it can be treated; approximately 90% of people survive for over 5 years if diagnosed at the earliest stage (known as Dukes A).

Screening programmes can identify people with the disease before any symptoms develop and so are important for successful treatment. However, compliance with screening, which typically involves a colonoscopy, is a problem. Less invasive procedures for bowel cancer detection are likely to improve compliance and could lead to earlier diagnosis and treatment.

Detection of bowel cancer biomarkers by a blood test is an attractive prospect; a blood test is less invasive than a colonoscopy, and can be easily carried out at GP surgeries and many healthcare systems already offer routine blood tests. In 2008, three blood-based biomarkers for bowel cancer were identified, including septin 9 (SEPT9) methylated DNA.

In a recent study published by BMC Medicine as part of the Clinical Biomarkers thematic series, Jorga Warren and colleagues describe a blood-based bowel cancer screening test for SEPT9 methylated DNA with better sensitivity and  specificity than previous tests for this biomarker. The study showed that 90% of all bowel cancers from different locations and stages can be detected by the SEPT9 blood test. Detection of this biomarker in the blood could provide an alternative to colonoscopy for screening, leading to improved compliance and further reductions in deaths from bowel cancer.