Table 4.
Colorectal cancer risk factors from a case note review of patients with colorectal adenoma who developed colorectal cancer and matched controls.
| Adenoma patients | |||
|---|---|---|---|
|
| |||
| Factor | Controls n=148 (%) |
CRC cases n=148 (%) |
Odds ratio a (95% CI) |
| Previous adenoma before 2000 | |||
| No/unknown | 132 (89.2) | 136 (91.9) | 1.00 |
| Yes | 16 (10.8) | 12 (8.1) | 0.69 (0.30–1.62) |
| Personal history of IBD | |||
| No/unknown | 137 (92.6) | 127 (85.8) | 1.00 |
| Yes | 11 (7.4) | 21 (14.2) | 2.25 (0.98–5.17) |
| Family history of CRC | |||
| No/unknown | 127 (85.8) | 130 (87.8) | 1.00 |
| Yes | 21 (14.2) | 18 (12.2) | 0.83 (0.42–1.65) |
| Presence of HGD | |||
| No/unknown | 135 (91.2) | 121 (81.8) | 1.00 |
| Yes | 13 (8.8) | 27 (18.2) | 3.33 (1.34–8.30) |
| No. incident polyps | |||
| 1 | 94 (63.5) | 105 (71.0) | 1.00 |
| ≥2 | 54 (36.5) | 43 (29.0) | 0.70 (0.43–1.16) |
| Right-sided polyp b | |||
| No/unknown | 134 (85.4) | 124 (83.8) | 1.00 |
| Yes, ≥1 right-sided | 23 (14.7) | 24 (16.2) | 1.22 (0.66–2.28) |
| Polyp size | |||
| Small/unknown | 112 (75.7) | 103 (69.6) | 1.00 |
| Large (≥1cm) | 36 (24.3) | 45 (30.4) | 1.35 (0.81–2.24) |
| Full colonoscopy c | |||
| No/unknown | 37 (25.0) | 50 (33.8) | 1.00 |
| Yes,1 | 49 (33.1) | 45 (30.4) | 0.66 (0.36–1.21) |
| Yes, ≥2 | 62 (41.9) | 53 (35.8) | 0.59 (0.32–1.09) |
| Any other investigations d | |||
| No/unknown | 23 (15.5) | 18 (12.2) | 1.20 (0.58–2.47) |
| Yes,1 e | 62 (41.9) | 38 (25.7) | 1.00 |
| Yes, ≥2 | 63 (42.6) | 92 (62.2) | 2.18 (1.32–3.60) |
| Did not attend for planned follow-up procedure | |||
| No/unknown | 137 (92.6) | 132 (89.2) | 1.00 |
| Yes | 10 (6.8) | 13 (8.8) | 1.45 (0.62–3.41) |
| Yes, missed>1 procedure | 1 (0.7) | 3 (2.0) | 3.64 (0.36–37.01) |
CRC: Colorectal cancer; HGD: High grade dysplasia; IBD: Inflammatory bowel disease.
Adjusted for matching criteria (age, sex, incident polyp type (adenoma/hyperplastic) and year of diagnosis at incident polyp.
Includes polyps detected in caecum, ascending colon, hepatic flexure and transverse colon
Number of full colonoscopies performed within 1 year prior to incident polyp diagnosis and before censor date (CRC diagnosis or matched follow-up time for controls).
Any other investigative procedures (excluding full colonoscopy) including incomplete or unspecified colonoscopy, proctoscopy, rigid or flexible sigmoidoscopy or barium enema performed within 1 year prior to incident polyp diagnosis.
Chosen as reference category to reflect that many individuals attended for a sigmoidoscopy or other non-full colonoscopy investigation at their first investigation, which was then followed up by a full colonoscopy.