Table 1

Characteristics of studies included in the systematic review

Study	Country	Design	Screening modality	Study period	Age	Standard care (n)	Screening group (n)	Men/women (n)	Adherence (%)	Follow-up (years)
Atkin 8 41 46 57	UK (UKFSST)	Volunteers	Sigmoidoscopy, once only	1994–1999	55–64	113 178	57 254	83 334 / 86 700	71	Median 17.1
Schoen 11 32 42 58 59	US (PLCO)	Volunteers	Sigmoidoscopy, twice	1993–2001	55–74	77 444	77 443	76 678 / 78 209	83.5	Mortality median 16.8; Incidence median 15.8
Segnan 11 43 60	Italy (SCORE)	Volunteers	Sigmoidoscopy, once only	1995–1999	55–64	17 144	17 148	17 235 / 17 158	57.8	Mortality median 11.4; Incidence median 10.5
Hoff 9 11 44 61–63	Norway (NORCCAP)	Population-based	Sigmoidoscopy, once only	1999–2001	50–64	79 430	20 780	49 191 / 49 601	65	Median 14.8
Mandel 25 31 38 64	USA (Minnesota)	Volunteers	gFOBT, annually* and biennially†	1975–1992	50–80	15 394	Annual: 15 570; Biennial: 15 587	Annual: 7489/8081; Biennial: 7444/8143	Annual: 90.2; Biennial: 89.9	Mortality: 30; Incidence: 18
Scholefield 29 34 35 48 65	England (Nottingham)	Population-based	gFOBT, biennially‡	1981–1995	45–74	76 384	76 253	72 172 / 78 079	59.6	Median 19.5
Kronborg 30 36 66	Denmark (Funen)	Population-based	gFOBT, biennially§	1985–2002	45–75	30 966	30 967	29 714 / 32 219	66.7	Max 17
Kewenter 37 49 67 68	Sweden (Gothenburg)	Population-based	gFOBT, biennially¶	1982–1995	60–64	34 164	34 144	NR	70	Mean 15.5
Pitkaniemi 39	Finland	Population-based	gFOBT, biennially**	2004–2012	60–69	181 085	181 080	179 519 / 180 973	68.8	Median 4.5
Quintero 69	Spain (COLONPREV)	Population-based	Colonoscopy, once only/FIT (15 µg/g), biennially**	2008–2011	50–69	NA	Colonoscopy: 28 708; FIT: 28 696	26 463 / 30 941	Colonoscopy: 24.6; FIT: 34.2	0
Bretthauer 70	Norway, Sweden, Poland, the Netherlands (NORDICC)	Population-based	Colonoscopy, once only	2009–2014	55–64	63 370	31 589	47 259 / 47 135	40.0	0
Kirkøen 47	Norway (BCSN)	Population-based	Sigmoidoscopy, once only/FIT (15 µg/g), biennially**	2001–2008	50–74	7650	Sigmoidoscopy: 7270; FIT: 6920	10 088 / 11 752	Sigmoidoscopy: 51; FIT: 57	0

*Eleven screening rounds over 15 years, with a 4-year hiatus.
†Six screening rounds over 15 years, with a 3-year hiatus.
‡Three to five screening rounds.
§Nine screening rounds.
¶Two to three screening rounds, interval between rounds maximum 10 years 2 months.
**Ongoing.
BCSN, Bowel Cancer Screening in Norway; COLONPREV, Colorectal Cancer Screening in Average-risk Population; FIT, faecal immunochemical test; gFOBT, guaiac faecal occult blood test; NORCCAP, Norwegian Colorectal Cancer Prevention trial; NORDICC, The Northern-European Initiative on Colorectal Cancer; PLCO, Prostate, Lung, Colorectal and Ovarian cancer screening trial; SCORE, Italian multicentre randomised controlled trial of once-only sigmoidoscopy; UKFSST, UK Flexible Sigmoidoscopy Screening Trial.