OBJECTIVE: Evaluate effectiveness, harms and burdens of faecal blood testing, sigmoidoscopy and colonoscopy screening for colorectal cancer over 15 years.
DESIGN: We performed an update of a Cochrane systematic review, and performed network meta-analysis comparing randomised trials evaluating colorectal cancer screening with guaiac faecal occult blood test (gFOBT) (annual, biennial), faecal immunochemical test (FIT) (annual, biennial), sigmoidoscopy (once-only) or colonoscopy (once-only) in a healthy population, aged 50-79 years. We conducted subgroup analysis on sex. Follow-up >5 years was required for analysis of colorectal cancer incidence and mortality.
RESULTS: 12 randomised trials proved eligible. Compared with no-screening, we found high certainty evidence for sigmoidoscopy screening slightly reducing colorectal cancer incidence (relative risk (RR) 0.76; 95% confidence interval (CI 0.70 to 0.83) and mortality (RR 0.74; 95% CI 0.69 to 0.80), while gFOBT screening had little or no difference on colorectal cancer incidence, but slightly reduced colorectal cancer mortality (annual: RR 0.69; 95% CI 0.56 to 0.86, biennial: RR 0.88; 95% CI 0.82 to 0.93). No screening test reduced mortality nor incidence by more than six per 1000 screened over 15 years. Sigmoidoscopy had a greater effect in men, for both colorectal cancer incidence (women: RR 0.86; 95% CI 0.81 to 0.92, men: RR 0.75, 95% CI 0.71 to 0.79), and mortality (women: RR 0.85; 95% CI 0.71 to 0.96, men: RR 0.67; 95% CI 0.61 to 0.75) (moderate certainty).
CONCLUSIONS: In a 15-year perspective, sigmoidoscopy reduces colorectal cancer incidence, while sigmoidoscopy, annual and biennial gFOBT all reduce colorectal cancer mortality. Sigmoidoscopy may reduce colorectal cancer incidence and mortality more in men than in women.
PROSPERO REGISTRATION NUMBER: CRD42018093401.
| Specialty Area | Score |
|---|---|
| Family Medicine (FM)/General Practice (GP) | |
| General Internal Medicine-Primary Care(US) | |
| Internal Medicine | |
| Oncology - Gastrointestinal | |
| Gastroenterology |
Rigorous summary of the literature, but the conclusions are not necessarily novel.
Although these findings may be viewed as consolidation for the evidence supporting the effectiveness of colorectal cancer screening, they are not surprising to most professionals in this field and are unlikely to change practice. What could be more informative is to compare different screening modalities in terms of cost-effectiveness.
It is reassuring that a single sigmoidoscopy can reduce colorectal cancer incidence and mortality at the 15-year mark. A greater effect was seen in males. This probably can be explained by the fact that women have a higher incidence of colonic adenomas and cancers in a more proximal location. Long-term results with FIT testing are eagerly awaited.
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