Randomized controlled trial: Flexible sigmoidoscopy as an adjunct to faecal occult blood testing in population screening

Abstract

Objectives Flexible sigmoidoscopy screening at around age 60 can reduce colorectal cancer incidence. Insufficient evidence exists on flexible sigmoidoscopy at age 60 in a population being offered biennial faecal occult blood test screening from age 50. This randomized controlled trial assessed if flexible sigmoidoscopy would be an effective adjunct to faecal occult blood test. Methods In the Scottish Bowel Screening Programme between June 2014 and December 2015, 51,769 individuals were randomized to be offered flexible sigmoidoscopy instead of faecal occult blood test at age 60 or to continue faecal occult blood test. Those not accepting flexible sigmoidoscopy and those with normal flexible sigmoidoscopy were offered faecal occult blood test. All with flexible sigmoidoscopy-detected neoplasia or a positive faecal occult blood test result were offered colonoscopy. Results Overall flexible sigmoidoscopy uptake was 17.8%, higher in men than women, and decreased with increasing deprivation (25.7% in the least to 9.2% in the most deprived quintile). In those who underwent flexible sigmoidoscopy, detection rate for colorectal cancer was 0.13%, for adenoma 7.27%, and for total neoplasia 7.40%. In those who underwent colonoscopy after a positive flexible sigmoidoscopy, detection rate for colorectal cancer was 0.28%, adenoma 8.66%, and total neoplasia 8.83%. On an intention to screen basis, there was no difference in colorectal cancer detection rate between the study and control groups. Adenoma and total neoplasia detection rate were significantly higher in the study group, with odds ratios of 5.95 (95%CI: 4.69–7.56) and 5.10 (95%CI: 4.09–6.35), respectively. Conclusions In a single screening round at age 60, there was low uptake and neoplasia detection rate. Flexible sigmoidoscopy detected significantly more neoplasia than faecal occult blood test alone.

Screening for Colorectal Cancer

“…Thirty-three unique fair- to good-quality studies (n = 10 776 276) (published in 66 articles) were included to assess the effectiveness or comparative effectiveness of screening tests on CRC incidence and mortality. These included 2 prospective cohort studies (n = 436 927) that examined the effectiveness of screening colonoscopy, 4 RCTs (n = 458 002) that examined the effectiveness of flexible sigmoidoscopy with or without a FIT, 6 trials (n = 525 966) that examined the effectiveness of a gFOBT, and 1 prospective cohort study (n = 5 417 699) that examined the effectiveness of a FIT.…”

“…These included 2 prospective cohort studies (n = 436 927) that examined the effectiveness of screening colonoscopy, 4 RCTs (n = 458 002) that examined the effectiveness of flexible sigmoidoscopy with or without a FIT, 6 trials (n = 525 966) that examined the effectiveness of a gFOBT, and 1 prospective cohort study (n = 5 417 699) that examined the effectiveness of a FIT. In addition to 1 screening RCT (n = 98 678) that evaluated flexible sigmoidoscopy plus FIT vs flexible sigmoidoscopy alone, 20 studies (n = 471 860) that compared screening modalities were included. The magnitude of benefit in CRC mortality and cancer incidence among screening tests could not be directly compared because of major differences in the design of included studies for each test type (eg, trial vs observational study, intention to screen vs as screened, outcome metric reported).…”

Characteristics of nonparticipants in a randomised colorectal cancer screening trial comparing sigmoidoscopy and faecal immunochemical testing

“…Participation is lowest in the lowest socioeconomic groups, 5,7‐10 population with nonnative ethnicity, 5,8,9 those living without a partner, 5,8 with earlier nonparticipation 8 and with major chronic diseases 11 . The socioeconomic gradient is also important in sigmoidoscopy screening, where participation is lower than in faecal‐based screening 12,13 . However, it is unknown whether sociodemographic factors predict participation in faecal‐based and sigmoidoscopy screening differently.…”

“…11 The socioeconomic gradient is also important in sigmoidoscopy screening, where participation is lower than in faecal-based screening. 12,13 However, it is unknown whether sociodemographic factors predict participation in faecal-based and sigmoidoscopy screening differently.…”

Flexible use of flexible sigmoidoscopy

“…1 In this edition of the journal, Steele et al report on a randomized controlled trial of the offer of guaiac faecal occult blood test (FOBT) alone or in conjunction with flexible sigmoidoscopy (FS) in people aged 60 in Scotland. 2 Compared with previous studies of FS, this trial had very low uptake: 17.8% overall, ranging from 7.4% among the most deprived women to 28.6% among the least deprived men.…”