Table 3.
Risk of colorectal cancer (CRC) according to number of first degree relatives (FDRs, parents and siblings) with a family history of polyps. Values are numbers (percentages) unless stated otherwise
| Polyp types in FDRs | Cases (n=68 060) | Controls (n=333 753) | Multivariable adjusted odds ratio (95% CI)* | Multivariable+family history of CRC adjusted odds ratio (95% CI)† |
|---|---|---|---|---|
| Any polyps | ||||
| No of FDRs with any polyps: | ||||
| 0 | 62 318 (91.6) | 314 893 (94.3) | 1 (Ref) | 1 (Ref) |
| 1 | 5220 (7.7) | 17 627 (5.3) | 1.58 (1.53 to 1.63) | 1.38 (1.33 to 1.43) |
| ≥2 | 522 (0.8) | 1233 (0.4) | 2.27 (2.03 to 2.53) | 1.70 (1.52 to 1.90) |
| P for trend | — | — | <0.001 | <0.001 |
| Youngest age at diagnosis of any polyps (years): | ||||
| ≥70 | 2466 (3.6) | 8502 (2.5) | 1.52 (1.45 to 1.60) | 1.29 (1.23 to 1.36) |
| 60-69 | 1753 (2.6) | 5724 (1.7) | 1.66 (1.57 to 1.76) | 1.44 (1.35 to 1.52) |
| 50-59 | 1085 (1.6) | 3464 (1.0) | 1.67 (1.56 to 1.80) | 1.48 (1.37 to 1.59) |
| <50 | 438 (0.6) | 1170 (0.4) | 2.00 (1.78 to 2.24) | 1.77 (1.57 to 1.99) |
| P for trend | — | — | <0.001 | <0.001 |
| Advanced polyps | ||||
| No of FDRs with advanced polyps: | ||||
| 0 | 65 866 (96.8) | 327 276 (98.1) | 1 (Ref) | 1 (Ref) |
| 1 | 2137 (3.1) | 6326 (1.9) | 1.76 (1.67 to 1.85) | 1.44 (1.36 to 1.52) |
| ≥2 | 57 (0.1) | 151 (0.0) | 1.93 (1.41 to 2.66) | 1.26 (0.91 to 1.75) |
| P for trend | — | — | <0.001 | <0.001 |
| Youngest diagnosis age of advanced polyps (years): | ||||
| ≥70 | 1067 (1.6) | 3451 (1.0) | 1.59 (1.48 to 1.71) | 1.29 (1.20 to 1.39) |
| 60-69 | 638 (0.9) | 1785 (0.5) | 1.87 (1.70 to 2.06) | 1.51 (1.37 to 1.67) |
| 50-59 | 371 (0.5) | 989 (0.3) | 1.98 (1.74 to 2.24) | 1.64 (1.45 to 1.87) |
| <50 | 118 (0.2) | 252 (0.1) | 2.57 (2.04 to 3.23) | 2.12 (1.68 to 2.68) |
| P for trend | — | — | <0.001 | <0.001 |
Multivariable conditional logistic regression was used to account for matching on age, sex, year of birth, and county of residence, and was further adjusted for year of birth (continuous), family size (continuous), income levels (fifths), education (≤9 years, 10-12 years, >12 years, missing), total number of previous clinic visits (fifths), number of previous endoscopies (0, 1, 2, ≥3), Charlson comorbidity index score (continuous), and major comorbidities (all binary, including diabetes, cardiovascular disease, non-colorectal cancer, liver disease, chronic pulmonary disease, connective tissue disease, and peptic ulcer disease).
Further adjusted for number of FDRs with a history of CRC (continuous).