Table 3.
Number of relatives and finding of adenomas and cancer at colonoscopy for patients with a family history of colorectal cancer
| Relatives | n | Cancer found at colonoscopy | Adenoma found at colonoscopy |
|---|---|---|---|
| 1 SDR | 102 | 2 (2.0%) | 20 (19.6%) |
| 2 SDRs | 62 | 1 (1.6%) | 18 (29.0%) |
| >2 SDRs | 46 | 2 (4.3%) | 3 (6.5%) |
| 1 FDR | 1,167 | 17 (1.5%) | 204 (17.5%) |
| 1 FDR + 1 SDR | 288 | 4 (1.4%) | 43 (14.9%) |
| 1 FDR + >1 SDR | 185 | 2 (1.1%) | 39 (21.1%) |
| 2 FDRs | 180 | 6 (3.3%) | 41 (22.8%) |
| 2 FDRs + 1 SDR | 33 | 2 (6.1%) | 4 (12.1%) |
| 2 FDRs + >1 SDR | 18 | 0 (0%) | 1 (5.6%) |
| >2 FDRs | 30 | 2 (6.7%) | 8 (26.7%) |
| >2 FDRs + 1 or >1 SDR | 5 | 0 (0%) | 1 (20.0%) |
| Not stated | 177 | 2 (1.1%) | 15 (8.5%) |
| Total | 2,293 | 40 (1.7%) | 397 (17.3%) |
Statistical comparisons
Patients with only SDRs versus those with FDRs:
- 5 cancers in those with SDRs (2.3%) vs 33 in those with FDRs (1.7%) (p=0.9)
- 41 adenomas in those with SDRs (19.5%) vs 340 in those with FDRs (17.9%) (p=0.7)
Patients with only one FDR versus those with more than one FDR:
- 23 cancers in those with 1 FDR (1.4%) vs 10 in those with >1 FDR (3.8%) (p=0.01)
- 286 adenomas in those with 1 FDR (21%) vs 54 in those with >1 FDR (21%) (p=0.6)
FDR = first-degree relative; SDR = second-degree relative