Table 1

Pros and cons of the three main screening modalities

Faecal occult blood (unhydrated, Haemoccult)Flexible sigmoidoscopyColonoscopy
CRC, colorectal cancer; FOB, faecal occult blood; FS, flexible sigmoidoscopy.
SettingHomeOPD endoscopyEndoscopy
Bowel prepNo (diet restriction possible)Self admin enemaFull bowel prep
StaffTesterNursePhysician, nurse, pathologist
Duration of procedure5 minutes. Longer in novices15–20 minutes. Longer in novices
Day off workNoNoYes
Success ratePredictive value for CRC of positive FOB: 5–10%312% return due to inadequate bowel prep32Completion rate in 79% of all cases33
Sensitivity for cancers or polyps > 1 cmCancers 50%,31 polyps 17–46%3495% cancer and high risk polyps3595% cancer and high risk polyps35
Specificity for cancers or polyps > 1 cmCancers 98%31100%36100%36
Cost (1999) of individual test$5 (2001),37 £14.338$99 (2001)37; £96 (1998)39$380 (2001)37 £138 (1998)39
Incremental cost effectiveness ratios  compared with no screening (per  year of life saved) 1998$12 6673 $970540 (annual non hydrated FOB)$16 7863 (annual non-hydrated FOB plus FS every 5 years)$20 418,3 $10 98340 (colonoscopy every 10 years)
Therapeutic (ability to remove polyps)NoNoYes (increases cost slightly)
Large intestine visualisedAbility to screen right sided pathologyRectum, sigmoid colon, and possibly descending colonWhole large intestine