Faecal immunochemical test (FIT)
A stool test for hidden blood, done at home every year. Positive results are followed by colonoscopy.
Antibody-based detection of human haemoglobin; sensitivity ~74% for cancer per round, low for adenomas; programmatic annual FIT approaches colonoscopy in modelled mortality benefit. Backbone of most European and Asian screening programmes.
A colonoscopy probably does reduce bowel cancer risk for the person who has it, but a programme that offers colonoscopy achieves much less if most people decline. Programmes based on stool tests with high uptake may deliver as much population benefit at lower cost and risk.
A cheap home stool test, repeated yearly or every two years and followed by colonoscopy when positive, prevents bowel cancer deaths. This is what national bowel screening programmes do today, with FIT replacing the older guaiac test.