Table 1.
Baseline characteristics of the nonsmoker controls (C), smokers (S), smoking lung-cancer group (TS), and nonsmoking lung-cancer group (TN).
| Group | Smokers | Nonsmokers | Age (years)∗ |
Age when started smoking (years) | Number of cigarettes per day | Number of years smoked (years) | Pack-years | Adenocarcinoma | Squamous cell carcinoma |
|---|---|---|---|---|---|---|---|---|---|
| C | — | 65 | 55.0 ± 10.2 | — | — | — | — | — | — |
| S | 100 | — | 53.9 ± 10.3 | 29.6 ± 8.2 | 34.1 ± 14.6 | 24.2 ± 9.5 | 43.3 ± 24.4 | — | — |
| TS | 53 | — | 56.5 ± 9.4 | 27.2 ± 8.2 | 39.0 ± 9.2 | 29.3 ± 9.8 | 56.4 ± 14.1 | 23 | 30 |
| TN | — | 31 | 56.7 ± 12.9 | — | — | — | — | 3 | 28 |
*The means and standard deviations are shown for age (years) and smoking status (pack-years).