Table 4.
Multivariable-adjusted hazard ratios and 95% confidence intervals for associations between quintile of baseline serum alpha-tocopherol concentration and lung cancer according to tumor histology and smoking years in the ATBC Study*
| Histological type | Quintiles of baseline serum alpha-tocopherol, range |
P trend † | ||||
|---|---|---|---|---|---|---|
| Q1 <9.5 mg/L | Q2 9.5–10.9 mg/L | Q3 10.9–12.3 mg/L | Q4 12.3–14.2 mg/L | Q5 ≥14.2 mg/L | ||
| HR (95% CI) | HR (95% CI) | HR (95% CI) | HR (95% CI) | HR (95% CI) | ||
| Squamous cell carcinoma (n = 959) | 1.00 (Ref) | 0.92 (0.76 to 1.12) | 0.82 (0.67 to 1.02) | 0.70 (0.56 to 0.87) | 0.80 (0.63 to 1.02) | .03 |
| <40 y of smoking | 1.00 (Ref) | 0.76 (0.57 to 1.01) | 0.79 (0.60 to 1.06) | 0.51 (0.37 to 0.71) | 0.60 (0.42 to 0.85) | .002 |
| ≥40 y of smoking | 1.00 (Ref) | 1.08 (0.83 to 1.41) | 0.82 (0.60 to 1.11) | 0.91 (0.67 to 1.24) | 1.03 (0.73 to 1.43) | .91 |
| Small cell carcinoma (n = 469) | 1.00 (Ref) | 1.09 (0.82 to 1.45) | 0.92 (0.68 to 1.26) | 0.85 (0.62 to 1.18) | 0.83 (0.58 to 1.18) | .14 |
| <40 y of smoking | 1.00 (Ref) | 0.74 (0.50 to 1.12) | 0.66 (0.43 to 1.01) | 0.63 (0.40 to 0.97) | 0.51 (0.31 to 0.85) | .02 |
| ≥40 y of smoking | 1.00 (Ref) | 1.58 (1.05 to 2.39) | 1.30 (0.83 to 2.05) | 1.15 (0.71 to 1.85) | 1.30 (0.78 to 2.17) | .76 |
| Adenocarcinoma (n = 427) | 1.00 (Ref) | 1.08 (0.80 to 1.45) | 0.83 (0.59 to 1.15) | 1.04 (0.75 to 1.45) | 0.81 (0.55 to 1.19) | .27 |
| <40 y of smoking | 1.00 (Ref) | 1.10 (0.73 to 1.66) | 0.72 (0.46 to 1.13) | 0.91 (0.58 to 1.43) | 0.67 (0.40 to 1.13) | .09 |
| ≥40 y of smoking | 1.00 (Ref) | 1.06 (0.68 to 1.64) | 1.00 (0.61 to 1.62) | 1.25 (0.77 to 2.03) | 1.03 (0.59 to 1.80) | .77 |
Cox proportional hazard regression using follow-up time as the time metric to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of associations between baseline serum alpha-tocopherol (quintiles) and incidence of lung cancer by tumor histology and years of smoking and adjusted for age at baseline, body mass index (BMI), years of cigarette smoking, number of cigarettes smoked daily, serum total cholesterol concentration, and trial intervention group. ATBC = Alpha-Tocopherol, Beta-Carotene Cancer Prevention; Q = quintile; Ref = referent.
Two-sided Ptrend is based on the statistical significance of the coefficient of the quintile variable (median value within each quintile).