Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and a leading cause of cancer death worldwide. In the UK it is the 4th most common cancer. The increase in colorectal cancer is linked with improved living standards – it is often termed a “western” disease.
CRC usually evolves slowly (>10 years) from premalignant adenomas, providing a good window of opportunity to detect cancer early. At least 95% of all CRC cases arise from pre-existing polypoid or flat adenomas. Often, CRC is diagnosed by investigation of symptoms, but screening for colorectal cancer increases the cancer detection rate at an early stage, and reduces mortality.
Risk Factors for CRC include:
familial adenomatous polyposis
ulcerative colitis and Crohn’s disease
Colorectal tumors and adenomatous polyps can bleed intermittently and so traces of blood appear in stools. Blood can be detected in stools by using highly selective tests that detect human Haemoglobin and Haemoglobin products. National Screening programmes operate in a number of countries worldwide (including UK) to detect blood in stools which enables the diagnosis of CRC to be made at an earlier, more curable stage.
According to the NCI SEER Program there has been a proximal shift in colorectal cancers over the last two decades, with more of the diseases being found further up the GI tract. One of the challenges faced as a result of this phenomenon is that Haemoglobin - the target in many screening tests - is not stable. Haemoglobin has been shown to degrade as it passes through the GI tract as a result of proteolytic activity in stool. However free Hb can separate into α-β molecules which become bound haptoglobin (Hp) to form a complex. Hb/Hp complex is resistant to acid and proteolytic degradation and is stable over the entire course of the large bowel. BIOHIT's ColonView Quick Test detects both Hb and Hb/Hp Complex therefore making it possible to detect proximal bleeds with a greater degree of confidence.