- Design
- Systematic review and meta-analysis of randomised and non-randomised studies
- Population
- Adults aged 45–75; RCTs 1,474,576 participants (gFOBT); non-RCTs 7,435,956 (FIT)
- Primary outcome
- All-cause and colorectal cancer mortality, incidence and stage IV incidence
- Effect
- CRC mortality RR 0.89 (95% CI 0.84–0.94); all-cause RR 1.00 (0.99–1.01)
This systematic review and meta-analysis assessed population colorectal cancer screening with faecal occult blood tests in adults aged 45 to 75. Randomised trials, all of guaiac tests (gFOBT), included 1,474,576 participants.
Colorectal cancer mortality fell (RR 0.89, 95% CI 0.84 to 0.94; moderate certainty), about 38 fewer deaths per 100,000 screened. All-cause mortality did not change (RR 1.00, 0.99 to 1.01). Trials showed no effect on incidence or stage IV disease. Non-randomised studies of faecal immunochemical tests (FIT) in 7.4 million people suggested much larger reductions in cancer death (RR 0.21) and in incidence and stage IV disease, but at low certainty.
These results support organised screening, and FIT, which is more sensitive than gFOBT, is the test of choice. India has no national colorectal screening programme, and incidence is lower than in the West but rising in younger adults. For individual patients, the choice to screen should be an informed one.
- Offer FIT rather than guaiac tests where stool-based screening is used.
- Explain that screening reduces colorectal cancer death but has not been shown to extend overall life expectancy.
- A positive FIT needs colonoscopy; screening only works if follow-up happens.
- A negative FIT does not rule out cancer in a symptomatic patient, such as one with rectal bleeding or anaemia; symptoms need diagnostic assessment, not screening.
Why it matters
It gives clinicians honest numbers for the screening conversation, including what screening does not do.
Don't overread it
The large FIT benefit comes from non-randomised data at low certainty.
The statistics, in plain English
A risk ratio of 0.89 means 11% fewer colorectal cancer deaths, about 38 per 100,000 people screened. The FIT estimate (RR 0.21) comes from non-randomised comparisons, where healthier people are more likely to take part, so it probably overstates the benefit.
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