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Table 1 Characteristics of age, gender and smoking status of cases and controls
From: Polymorphisms of XRCC1 genes and risk of nasopharyngeal carcinoma in the Cantonese population
| Variable | Cases(n= 462) | Controls (n= 511) |
|---|---|---|
| Gender | ||
| Male | 339 (73.4)a | 252 (49.1) |
| Female | 123 (26.6)a | 259 (50.9) |
| Age range (yr) | ||
| <60 | 395 (85.5)b | 422 (82.6) |
| ≥60 | 67 (14.5)b | 89 (17.4) |
| Mean age in years (S. D.) | 45.9 (12.2) | 45.7 (15.6) |
| Smoking status a | ||
| No | 164 (35.5)c | 353 (69.1) |
| Yes | 298 (64.5)c | 158 (30.9) |
| Pack-years smoked | ||
| <20 | 103 (34.6)d | 70 (44.3) |
| ≥20 | 195 (65.4)d | 88 (55.7) |
| Mean pack-years smoked (S.D.) | 16.1 (17.2) | 22.8 (17.3) |
| Median pack-years smoked (S.D.) | 20 (15.6) | 20 (17.3) |
