Overview of studies on interval CRCs after flexible sigmoidoscopy (FS)
| Studies | Definition iCRC | Design | Outcomes | Stage of CRC (I–II vs. III–IV) | Location of CRC (proximal vs. distal) | Risk factors/ possible aetiology |
|---|---|---|---|---|---|---|
| Schoen et al (2012)58 USA | Screen detected: <12 months of positive FS; not detectable: stage I-II and >30 months; or stage III–IV >48 months; prevalent non-detected: stage I–II detected <30 months or stage III–IV <48 months | PLCO multicentre trial; 77 447 intervention group | CRC incidence 977 CRCs: 243 screen detected 470 not detectable 264 prevalent non-detected | Screen detected: 184 vs. 59 Prevalent not detected: 95 vs. 169 Not detectable: 256 vs. 214 | Screen detected: 46 vs. 197 Prevalent not detected: 171 vs. 93 Not detectable: 310 vs. 158 | Possible aetiology |
| Segnan et al (2011)5 Italy | Not specifically detailed | RCT; 17 136 intervention group of which 9911 attenders; 17 136 controls | CRC incidence and mortality Intervention group: 251 CRCs; controls: 306 CRCs | Screen detected: 78 vs. 48; Not screened: 61 vs. 64; Control: 154 vs. 152 | Screen detected: 55 vs. 71; Not screened: 44 vs. 81; Control: 108 vs. 198 | N/A |
| Atkin et al (2010)4 UK | Not specifically detailed | Multicentre RCT, screening cohort; 40.674 intervention group, vs. 113.195 control group | CRC incidence and mortality Intervention group: 706 CRCs; controls 1818 CRCs | Not specified | Intervention: 311 vs. 386; controls: 628 vs. 1192 | N/A |
| Hoff et al (2009)57 Norway | Postscreen detected CRCs | RCT screening cohort; 13.653 screened vs. 41.092 controls | CRC incidence: 33 screen detected CRC; 38 postscreen detected CRC; 52 non-attenders; 362 controls | Screen detected: 20 vs. 11; postscreen detected: 6 vs. 29; non-attenders: 7 vs. 38; controls: 62 vs. 262 | Screen detected: 9 vs. 24; postscreen detected 27 vs.11; non-attenders; controls: 145 vs. 217 | N/A |
CRC, colorectal cancer; iCRC, interval CRC; N/A, not applicable; PLCO, Prostate, Lung, Colorectal, and Ovarian.