Table 1

Comparison of 20103 and 20201 risk stratifications of participants in the Northern Ireland bowel cancer screening programme, for those having polyp specimens submitted at index colonoscopy (n=3122)

2020 surveillance algorithm2010 surveillance algorithm
High risk (%)
(1 year)
Intermediate risk (%)
(3 years)
Low risk (%)
(5 years)
No risk (%)
(no surveillance)
Totals (%)
High risk
(3 years)
316 (100)268 (29.5)24 (1.8)1 (0.2)609 (19.5)*
Not high risk
(no surveillance)
0 (0.0)640 (70.5)1296 (98.2)577 (99.8)2513 (80.5)
Totals (%)316 (10.1)908 (29.1)1320 (42.3)578 (18.5)3122 (100)
  • *These 609 high-risk cases under 2020 guidance (see ref. 1 for definitions) comprise: 371 cases with advanced polyp (AP) plus 1–3 other premalignant polyps (PMP) but total <5; 114 cases with ≥5 PMPs but no APs; 101 cases with ≥5 PMPs and at least 1 AP; 23 cases with an isolated large (≥20 mm), large non-pedunculated colorectal polyp and no other PMPs.