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Lancet. 2010 May 8;375(9726):1624-33. doi: 10.1016/S0140-6736(10)60551-X. Epub 2010 Apr 27.

Once-only flexible sigmoidoscopy screening in prevention of colorectal cancer: a multicentre randomised controlled trial.

Collaborators (233)

Wooldrage K, Duffy S, Cuzick J, Atkin WS, Cuzick J, Hart AR, Wardle J, Edwards R, Northover JM, Edwards R, Atkin WS, Edwards S, Parkin M, Moss S, Kralj-Hans I, Edwards R, MacRae E, Edwards S, Shah U, Patel R, Kavanagh KP, Frost MV, Rao A, Baron CM, Edwards SL, Wale CJ, Talbot IC, Williams GT, Mackay EH, Quirke P, Warren BF, Williams CB, Hart AR, Saunders BP, Bell GD, Leicester RJ, Swarbrick ET, Thomas WM, Vellacott KD, Northover JM, Finan PJ, Mortensen NJ, Thomas WM, Thompson MR, Mackay EH, Montefiore DS, Moss S, Quirke P, Shepherd NA, Talbot IC, Warren B, Weischede S, Williams GT, Risio M, Senore C, Atkin WS, Cuzick J, Edwards R, Kralj-Hans I, Northover JM, Wardle J, Day NE, Spiegelhalter DJ, Fallowfield LJ, Frankel S, Maynard AK, McArdle CS, Wilson E, Whynes D, Hart AR, Pascoe AL, Painter JE, McKain ES, Ahmad SS, Martin JP, Evans RC, Green MS, Adams C, Watson MA, Macklin CP, Iskander NY, Cecil TD, Hanson JM, McIntyre PB, Aubrey R, Mayberry JF, Wicks AC, Thomas WM, McArdle CS, Finlay I, Cooke TG, Anderson JH, Beynon J, Carr ND, Jacyna MR, Vellacott KD, Radcliffe AG, Kennedy HJ, Stebbings WS, Thompson MR, Senapati A, Hobbiss JH, Watson AJ, O'Dwyer ST, Finan PJ, Rhodes JM, Cunliffe WJ, Griffiths CD, Varma J, Mortensen NJ, Morton DG, Keighley MR, McIntyre PB, Aubrey R, Mackay EH, Foulis AK, Howell S, Talbot IC, Thompson IW, Dallimore NS, Sams VR, Marley NJ, Wells S, Shanks JH, Haboubi NY, Quirke P, Campbell F, Bennett MK, Warren BF, Sanders DS, Fattah A, Al Izzi M, Barker F, Harrison R, Hemingway D, Scott A, de Caestecker J, Sharpe D, Duthie F, Swan L, Foulis A, Mckee R, McLellan DR, Williams N, Thomas E, John S, Pilley E, Jones M, Williams G, Radcliffe A, Torkington J, Sams V, Cletheroe L, Kapur S, Wharton R, Sargen K, Speakman CT, Stebbings W, Wright S, Flashman K, Bisset D, Hobbiss JH, Jones R, Warburton N, Parkinson M, Senior P, Sagar PM, Jayne D, Ambrose NS, Finan P, Ghanouni A, Campbell F, Reid P, Sheard J, Austin T, Skaife P, Morgan S, Kiff RS, Fitzgerald-Smith A, Tweedy L, Henry JA, Plusa SM, Butler D, Warren BF, Lane L, Cunningham C, Moore J, Bradbury J, Morton D, Stewart S, Colloby P, Rashbass J, Wright K, Gavin A, Middleton R, Moran T, Jones C, Bishop S, Flatt G, Shack L, Forman D, Deer P, Day M, Morris E, Thomas J, Roche M, Kennedy N, Brewster D, Storey C, McDonald A, Taylor R, Verne J, Pring A, Iles M, Møller H, Mak V, Maddams J, Okello C, Hanchett N, Meechan D, Smith A, Stewart J, Vipond L, Lawrence G, Madurasinghe V, Oakes R, Barrett G, Wall P, Gray J, Goldblatt P, Loveday A, Dewane S, Fitzpatrick S.

Author information

Department of Surgery and Cancer, Imperial College London, London, UK.



Colorectal cancer is the third most common cancer worldwide and has a high mortality rate. We tested the hypothesis that only one flexible sigmoidoscopy screening between 55 and 64 years of age can substantially reduce colorectal cancer incidence and mortality.


This randomised controlled trial was undertaken in 14 UK centres. 170 432 eligible men and women, who had indicated on a previous questionnaire that they would accept an invitation for screening, were randomly allocated to the intervention group (offered flexible sigmoidoscopy screening) or the control group (not contacted). Randomisation by sequential number generation was done centrally in blocks of 12, with stratification by trial centre, general practice, and household type. The primary outcomes were the incidence of colorectal cancer, including prevalent cases detected at screening, and mortality from colorectal cancer. Analyses were intention to treat and per protocol. The trial is registered, number ISRCTN28352761.


113 195 people were assigned to the control group and 57 237 to the intervention group, of whom 112 939 and 57 099, respectively, were included in the final analyses. 40 674 (71%) people underwent flexible sigmoidoscopy. During screening and median follow-up of 11.2 years (IQR 10.7-11.9), 2524 participants were diagnosed with colorectal cancer (1818 in control group vs 706 in intervention group) and 20 543 died (13 768 vs 6775; 727 certified from colorectal cancer [538 vs 189]). In intention-to-treat analyses, colorectal cancer incidence in the intervention group was reduced by 23% (hazard ratio 0.77, 95% CI 0.70-0.84) and mortality by 31% (0.69, 0.59-0.82). In per-protocol analyses, adjusting for self-selection bias in the intervention group, incidence of colorectal cancer in people attending screening was reduced by 33% (0.67, 0.60-0.76) and mortality by 43% (0.57, 0.45-0.72). Incidence of distal colorectal cancer (rectum and sigmoid colon) was reduced by 50% (0.50, 0.42-0.59; secondary outcome). The numbers needed to be screened to prevent one colorectal cancer diagnosis or death, by the end of the study period, were 191 (95% CI 145-277) and 489 (343-852), respectively.


Flexible sigmoidoscopy is a safe and practical test and, when offered only once between ages 55 and 64 years, confers a substantial and longlasting benefit.


Medical Research Council, National Health Service R&D, Cancer Research UK, KeyMed.

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