Table 3.
Association between quartiles of smoking pack-years and individual molecular subtypes of colorectal cancer compared with nonsmokers
| Marker and status | No. of cases | Smoking, pack-years |
P trend a | P difference b | |||
|---|---|---|---|---|---|---|---|
| Quartile 1 OR (95% CI) | Quartile 2 OR (95% CI) | Quartile 3 OR (95% CI) | Quartile 4 OR (95% CI) | ||||
| BRAF | |||||||
| mut | 921 | 0.81 (0.62 to 1.06) | 1.49 (1.20 to 1.84) | 1.69 (1.37 to 2.08) | 1.92 (1.58 to 2.33) | 1.0 x 10-14 | |
| wt | 7233 | 0.99 (0.89 to 1.11) | 1.21 (1.09 to 1.34) | 1.16 (1.05 to 1.29) | 1.37 (1.24 to 1.51) | 2.5 x 10-11 | 2.7 x 10-6 |
| KRAS | |||||||
| mut | 2331 | 1.04 (0.89 to 1.21) | 1.12 (0.96 to 1.29) | 1.17 (1.01 to 1.35) | 1.23 (1.07 to 1.41) | 1.0 x 10-3 | |
| Wt | 4547 | 0.93 (0.82 to 1.06) | 1.28 (1.14 to 1.43) | 1.22 (1.09 to 1.37) | 1.48 (1.33 to 1.65) | 2.1 x 10-14 | 9.6 x 10-3 |
| CIMP | |||||||
| + | 1247 | 1.05 (0.85 to 1.30) | 1.33 (1.09 to 1.62) | 1.62 (1.34 to 1.95) | 1.90 (1.60 to 2.26) | 8.9 x 10-16 | |
| − | 5966 | 1.00 (0.89 to 1.12) | 1.20 (1.08 to 1.33) | 1.15 (1.03 to 1.28) | 1.35 (1.22 to 1.49) | 2.1 x 10-9 | 2.4 x 10-6 |
| MSI | |||||||
| MSI-H | 1239 | 1.10 (0.90 to 1.35) | 1.26 (1.04 to 1.53) | 1.53 (1.28 to 1.84) | 1.66 (1.39 to 1.99) | 9.0 x 10-11 | |
| MSI-L/MSS | 7255 | 0.98 (0.89 to 1.09) | 1.24 (1.12 to 1.36) | 1.16 (1.05 to 1.29) | 1.38 (1.25 to 1.52) | 7.0 x 10-12 | 3.9 x 10-3 |
a
Two-sided Wald test was used to calculate the P values from the case-control analysis (N controls = 10 199). A Bonferroni corrected P value threshold of 6.3 x 10-3 was used for case-control analyses. CI = confidence interval; CIMP = CpG island methylation phenotype; MSI = microsatellite instability; MSI-H = MSI-high; MSI-L = MSI-low; MSS = microsatellite stable; mut = mutated; OR = odds ratio; wt = wild type.
b
Two-sided Wald test was used to calculate the P values from the case-only analysis. A Bonferroni corrected P value threshold of .013 for case-only analyses.