The immunochemical faecal occult blood test (FOBT) is a simpler way of identifying individuals who might have colorectal cancer, researchers claim in an article published online in The Lancet Oncology. Conventionally, guaiac FOBT is used to screen individuals who might be having this cancer, but this new test "could decrease substantially the number of false positives in a screening programme for colorectal cancer."
Lead author Dr Callum G Fraser also said that this could decrease the need for the tedious process of colonoscopy. The guaiac-based FOBT is used to screen individuals for colorectal cancer at present and works by detecting blood in the faeces. But this test is not always accurate and is known to have low clinical sensitivity. This is because a positive result does not always signify cancer. But individuals who test positive are often subjected to the more expensive colonoscopy, which can be avoided with the immunochemical test. In the current study, 1486 participants whose guaiac FOBT was positive were tested for the immunochemical FOBT. Out of there around 50 percent participated in the study. It was found that 22 percent tested negative in both samples, 16 percent in one sample and 62 percent in both samples. In the first and second groups, only one participant was found to have cancer. "Although immunochemical FOBT is more expensive than guaiac FOBT, its use in testing those who are weak positive on initial guaiac FOBT would reduce the need for colonoscopy by about 30%. The implications for national screening programmes are important in terms of reducing costs, inconvenience, and associated morbidity, without compromising the effectiveness of screening," Dr Fraser concluded.