Table 1.
Baseline Characteristics of the Included Studies
|
SPIRIT domain/RCT |
Bretthauer 2022 (NordICC) | Atkin 2017 (UKFSST) | Holmes 2014 (NORCCAP) | Schoen 2012 (PLCO) | Segnan 2011 (SCORE) |
|---|---|---|---|---|---|
| Country | Poland, Norway, Sweden, and Netherlands | England, Wales, and Scotland | Norway | United States | Italy |
| Study period | 2009–2014 | 1994–1999 | 1998–2011 | 1993–2001 | 1995–1999 |
| Age group, y | 55–64 | 55–64 | 50–64 | 55–74 | 55–64 |
| Intervention | Colonoscopy | Flexible sigmoidoscopy | Flexible sigmoidoscopy or combination of flexible sigmoidoscopy and FOBT | Flexible sigmoidoscopy | Flexible sigmoidoscopy |
| Total people randomized | 84,585 | 170,432 | 100,210 | 154,900 | 236,568 |
| Total people invited to screening | 28,220 | 57,237 | 20,572 | 77,445 | 17,136 |
| Adherent (underwent screening), n (%) | 11,843 (42%) | 40,621 (71%) | 12,955 (63%) | 64,653 (83.5%) | 9911 (57.8%) |
| Nonadherent (did not undergo screening), n (%) | 16,377 (58%) | 16,616 (29%) | 7617 (37%) | 12,792 (16.5%) | 7225 (42.2%) |
| Control (nonscreening) group | 56,365 | 11,2939 | 78,220 | 77,455 | 17,136 |
| Primary outcome | Risks of colorectal cancer and related death | Incidence of colorectal cancer, including prevalent cases detected at screening, and mortality from colorectal cancer | Colorectal cancer incidence and mortality | Death from colorectal cancer | CRC incidence and CRC-specific mortality |
| Final RCT conclusion | The risk of colorectal cancer at 10 y was lower among participants who were invited to undergo screening colonoscopy than among those who were assigned to no screening. | Flexible sigmoidoscopy is a safe and practical test and, when offered only once between ages 55 and 64 y, confers a substantial and long-lasting benefit. | In Norway, once-only flexible sigmoidoscopy screening or flexible sigmoidoscopy and FOBT reduced colorectal cancer incidence and mortality on a population level compared with no screening. Screening was effective both in the 50- to 54-y and the 55- to 64-y age groups. | Screening with flexible sigmoidoscopy was associated with a significant decrease in colorectal-cancer incidence (in both the distal and proximal colon) and mortality (distal colon only). | A single flexible sigmoidoscopy screening between ages 55 and 64 y was associated with a substantial reduction of CRC incidence and mortality. |
CRC, colorectal cancer; FOBT, fecal occult blood testing; NORCCAP, Norwegian Colorectal Cancer Prevention; NordICC,Nordic-European Initiative on Colorectal Cancer; PLCO, Prostate, Lung, Colorectal, and Ovarian; RCT, randomized controlled trial; SCORE, Screening for Colorectal; SPIRIT, Standard Protocol Items: Recommendations for Interventional Trials; UKFSST, United Kingdom Flexible Sigmoidoscopy Screening Trial.