Potential number of colorectal cancers (CRCs) detected by a screening programme combining flexible sigmoidoscopy (FS) with faecal occult blood testing (FOBT) (excluding those of unknown site and categorising multiple tumours as rectal as they are likely to be detected by FS)
| No (%) CRC potentially detected by screening programme | |||
| 1976–78 | 1990–97 | ||
| Site | % of CRC possibly detected by FS | ||
| Proximal | 3.3 | 9.6 | 62.4 |
| Distal | 74.4 | 252.2 | 1040.1 |
| Rectal | 96.5 | 531.7 | 1623.1 |
| Subtotal | 793.6 | 2725.6 | |
| 22.6% of undiagnosed proximal CRCs detected indirectly23 | +63.8 | +413.0 | |
| Subtotal | 857.4 | 3138.6 | |
| 51% non-compliant13 | −437.3 | −1600.1 | |
| 25% of remaining undiagnosed CRCs detected by FOBT28 29 | +190.5 | +858.0 | |
| Total | 610.6 (51.7) | 2396.5 (48.2) | |