Table 2.
Associations of smoking with early- and late-CRC risk
| Smoking exposure | <55 years |
≥55 years |
P (interaction) c | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Cases | Controls | ORa (95% CI) | ORb (95% CI) | Cases | Controls | ORa (95% CI) | ORb (95% CI) | ||
| No. (%) | No. (%) | No. (%) | No. (%) | ||||||
| Smoking status | .40 | ||||||||
| Never | 277 (38) | 391 (50) | 1 (Ref) | 1 (Ref) | 2527 (46) | 3141 (52) | 1 (Ref) | 1 (Ref) | |
| Former | 216 (30) | 208 (26) | 1.47 (1.15 to 1.88) | 1.39 (1.07 to 1.81) | 2267 (41) | 2333 (38) | 1.25 (1.15 to 1.35) | 1.24 (1.13 to 1.36) | |
| Current | 231 (32) | 188 (24) | 1.74 (1.36 to 2.23) | 1.57 (1.20 to 2.04) | 746 (13) | 605 (10) | 1.60 (1.41 to 1.81) | 1.46 (1.28 to 1.67) | |
| Pack-years | .20 | ||||||||
| 0 | 277 (38) | 391 (50) | 1 (Ref) | 1 (Ref) | 2527 (46) | 3141 (52) | 1 (Ref) | 1 (Ref) | |
| 1-15 | 242 (33) | 237 (30) | 1.44 (1.14 to 1.83) | 1.39 (1.08 to 1.79) | 1444 (26) | 1514 (25) | 1.22 (1.11 to 1.34) | 1.25 (1.13 to 1.38) | |
| ≥16 | 205 (29) | 159 (20) | 1.85 (1.42 to 2.41) | 1.61 (1.21 to 2.14) | 1569 (28) | 1424 (23) | 1.43 (1.31 to 1.57) | 1.33 (1.20 to 1.48) | |
| Per 10 pack-years | 1.22 (1.11 to 1.33) | 1.15 (1.05 to 1.27) | 1.07 (1.05 to 1.10) | 1.05 (1.03 to 1.08) | |||||
a
Adjusted for age and sex. CI = confidence interval; NSAIDs = nonsteroidal antiinflammatory drugs; OR = odds ratio; Ref = reference.
b
Additionally adjusted for previous endoscopy, family history of CRC, education, BMI approximately 10 years before diagnosis (cases) or interview (controls), alcohol consumption, NSAID use (including aspirin), physical activity, and diabetes.
c
P interaction between age (<55 or ≥55 years) and smoking exposure in the comprehensively adjusted model (model B).