CTC abnormalities, confirmatory tests and detection of matched abnormalities stratified by size of abnormality shown on CTC
| Largest abnormality suspected at CTC in 2731 gFOBt-positive individuals | |||||
|---|---|---|---|---|---|
| CRC or 10 mm+ polyp | 6–9 mm polyp | ≤5 mm polyp | Size not recorded | Any suspected polyp/cancer | |
| Number (% of total, (95% CI)) | 462 (16.9% (14.9% to 18.9%)) | 176 (6.4% (5.1% to 7.7%)) | 115 (4.2% (3.2% to 5.2%)) | 274 (10.0% (7.2% to 13.1%)) | 1027 (37.6% (33.8% to 41.4%)) |
| Number (% of those with CTC abnormality) undergoing confirmatory test (95% CI) | 427 of 462 (92.4% (89.6% to 95.1%)) | 136 of 176 (77.3% (70.8% to 83.7%)) | 76 of 115 (66.1% (53.2% to 79.7%)) | 272 of 274 (99.3% (98.3% to 100%)) | 911 of 1027 (88.7% (86.2% to 91.4%)) |
| Number (% of total) with matched abnormality (95% CI) | 371 (13.6% (11.4% to 15.7%)) | 99 (3.6% (2.6% to 4.6%)) | 40 (1.5% 0.9 to 2.0%)) | 147 (5.4% (3.6% to 7.2%)) | 657 (24.1% (41.5% to 26.7%)) |
| Histological diagnoses | 106 CRC 247 adenomas 18 non-adenomatous polyps | 87 adenomas 12 non-adenomatous polyps | 22 adenomas 18 non-adenomatous polyps | 18 CRC 112 adenomas 17 non-adenomatous polyps | 124 CRC 468 adenomas 65 non-adenomatous polyps |
| Positive predictive value for matched CRC or polyp (95% CI) | 86.9% (82.7% to 90.9%) | 72.8% (62.8% to 82.7%) | 52.6% (43.5% to 61.4%) | 54.0% (46.1% to 62.2%) | 72.1% (66.6% to 77.6%) |
| Positive predictive value for matched CRC or adenoma (95% CI) | 82.7% (78.6% to 86.5%) | 64.0% (52.3% to 74.9%) | 28.9% (18.3% to 39.5%) | 47.8% (38.8% to 53.6%) | 64.9% (59.3% to 70.5%) |
CRC, Colorectal cancer; CTC, CT colonography; gFOBt, guaiac faecal occult blood test.