Sensitive FIT test for faecal haemoglobin and Hb/Hp complex
The BIOHIT ColonView Hb and Hb/Hp tests are designed for the rapid identification of lower gastrointestinal (GI) organic abnormalities, including colorectal cancers and large adenomas that bleed. ColonView represents a state-of-the-art lateral flow faecal immunochemical test (FIT) that swiftly detects hidden blood in stool samples enabling the selection of patients who require follow up and referral for further investigations. This test relies on highly sensitive immunochemical detection of human haemoglobin (Hb) and human haemoglobin/haptoglobin (Hb/Hp) complexes by incorporating highly specific antibodies that target each of the biomarkers. Each test cassette features two test strips: one for Hb and another for the Hb/Hp complex, allowing the same sample to be used for both assessments. The ColonView quick test can identify both proximal and distal colorectal neoplasms that bleed.
For added convenience, the ColonView test can be assessed using the BIOHIT Quick Test Reader. This eliminates the need for user-based visual interpretation and enables direct result transmission to laboratory information systems (LIMS) if necessary.
Colorectal Cancer Screening in stool samples
The routine practice of detecting hidden blood in faeces plays a crucial role in the early detection and diagnosis of colorectal cancer and other organic intestinal diseases. This involves analysing stool samples for intact human haemoglobin (Hb) or its breakdown products, which enables effective bowel cancer screening programs in asymptomatic individuals as well as investigating abdominal symptoms in specific patient groups. It’s well-documented that Hb can degrade as it passes through the intestines due to microbial and endogenous enzymatic processes. When this degradation occurs, some assays may not recognise the altered Hb molecule, leading to false negative results.
A haemoglobin (Hb) molecule comprises two pairs of peptide chains (α- and β-globins) and four heme groups, each containing an iron atom. Free Hb can separate into α-β molecules, which bind to a protein known as haptoglobin (Hp). The Hb/Hp complex plays a vital role in recovering Hb from ruptured red blood cells and is relatively resistant to acid and proteolytic degradation. This means that the Hb/Hp complex can still be detected even after an extended passage through the bowel, increasing the likelihood of detecting blood from larger intestinal polyps and proximal colorectal cancers.
Colorectal cancer disease background
Colorectal cancer (CRC), encompassing colon and rectal malignancies, remains a prominent global health concern, contributing to significant cancer-related illness and death. Each year, there are more than 1.8 million new cases with over 850,000 deaths worldwide. Colorectal cancer encompasses malignancies developing in the colon and rectum, with proximal cancers situated in the caecum, ascending and transverse colon, and distal cancers found in the descending colon, sigmoid colon, and rectum.
Most colorectal cancer cases are sporadic, and about 75% occur in individuals considered to have moderate risk. Approximately 20% of cases have a family history of the disease, while the remaining 80% are associated with factors like inflammatory bowel disease (e.g. ulcerative colitis) or specific gene mutations (familial adenomatous polyposis or hereditary non-polyposis colorectal cancer). Studies have shown that individuals with first-degree relatives having colorectal cancer face a more than twofold increase in risk.
Notably, it is believed that at least 95% of colorectal cancer cases originate from identifiable precursors, such as adenomatous polyps and flat adenomas. This understanding is based on extensive population studies, which indicate a substantially higher bowel cancer risk for individuals with hereditary polyposis syndromes. Additionally, follow-up studies have shown a 60% to 90% reduction in colorectal cancer development among those who undergo endoscopic polyp removal (polypectomy).
Stool tests such as FITs are quite accurate for detecting blood in the stool which may indicate colorectal cancer, but they may also produce non-disease specific positive results due to other non-cancerous causes of bleeding. Sensitivity can vary and they are generally less sensitive than colonoscopy for detecting precancerous polyps or early-stage cancer, but a positive FIT test in an individual who also has a low serum Hb has good predictive value for colorectal cancer.
