Stool-based screening reduced colorectal cancer deaths, though not deaths overall

Design

Systematic review and meta-analysis of RCTs and non-randomised studies

Population

Adults aged 45–75; 1.47 million in RCTs, 7.4 million in non-randomised FIT studies

Primary outcome

All-cause mortality, colorectal cancer mortality, incidence and stage IV incidence

Effect

CRC mortality RR 0.89 (95% CI 0.84–0.94) in gFOBT RCTs; all-cause RR 1.00 (0.99–1.01)

This systematic review pooled studies of population colorectal cancer screening with faecal occult blood tests — guaiac tests (gFOBT) or faecal immunochemical tests (FIT) — in adults aged 45 to 75, compared with no screening.

Randomised trials of guaiac testing, with about 1.5 million participants, reduced colorectal cancer mortality (RR 0.89, 95% CI 0.84–0.94), about 38 fewer deaths per 100,000 screened, with moderate certainty. All-cause mortality did not change (RR 1.00). Trials showed no significant effect on cancer incidence or stage IV disease. Non-randomised studies of FIT, with 7.4 million people, suggested much larger reductions in cancer deaths, incidence and late-stage disease, but with low certainty.

FIT is more sensitive than the older guaiac test, so the randomised benefit is likely a floor. For family physicians in India, where there is no organised national colorectal screening programme, this supports offering FIT to adults aged 45–75, particularly those with risk factors, and arranging colonoscopy for any positive result.

• Offer FIT-based colorectal screening to average-risk adults aged 45–75 where resources allow.
• Arrange colonoscopy for every positive FIT; an unfollowed positive result gives no benefit.
• Explain the benefit honestly: fewer colorectal cancer deaths, but no measurable change in overall deaths.
• Do not use FIT to investigate symptoms such as rectal bleeding or anaemia without a proper pathway.
• Repeat FIT every one to two years; a single negative test is not lifelong reassurance.

Why it matters

It gives the honest numbers needed for a shared screening decision in clinics where screening is opportunistic.

Don't overread it

The large FIT benefit is from observational data with low certainty; randomised evidence is for the older guaiac test.

The statistics, in plain English

A risk ratio of 0.89 means an 11% relative reduction in colorectal cancer deaths — in absolute terms, 38 fewer deaths per 100,000 people screened. All-cause mortality did not change because colorectal cancer is a small share of all deaths, so any benefit is too small to see in the total. The very large FIT effect (RR 0.21) comes from non-randomised studies, where healthier people choose to be screened.

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