Table 4.
Risk of incident lung cancer according to a smoking category within each genetic-risk category.
| Subgroup | Total no. of participants | No. of lung cancer cases (%) | Person-years | IRa | HR (95% CI)b | P value | P for trend | P for interaction |
|---|---|---|---|---|---|---|---|---|
| Genetic risk and smoking status | ||||||||
| Low genetic risk | 0.132 | |||||||
| Never-smoking | 44,000 | 42 (0.10) | 313,454 | 0.13 | 1 (reference) | <0.001 | ||
| Former smoking | 18,217 | 111 (0.61) | 128,900 | 0.86 | 4.61 (3.2–6.64) | <0.001 | ||
| Current smoking | 6938 | 95 (1.37) | 49,031 | 1.94 | 10.75 (7.28–15.88) | <0.001 | ||
| Intermediate genetic risk | ||||||||
| Never-smoking | 133,002 | 156 (0.12) | 947,480 | 0.16 | 1 (reference) | <0.001 | ||
| Former smoking | 54307 | 426 (0.78) | 383,471 | 1.11 | 5.22 (4.33–6.29) | <0.001 | ||
| Current smoking | 20156 | 437 (2.17) | 141,808 | 3.08 | 14.86 (12.22–18.07) | <0.001 | ||
| High genetic risk | ||||||||
| Never-smoking | 44071 | 56 (0.13) | 313,775 | 0.18 | 1 (reference) | <0.001 | ||
| Former smoking | 18203 | 181 (0.99) | 128,421 | 1.41 | 6.19 (4.56–8.41) | <0.001 | ||
| Current smoking | 6900 | 183 (2.65) | 48,575 | 3.77 | 16.85 (12.25–23.19) | <0.001 | ||
| Genetic risk and smoking pack-years | ||||||||
| Low genetic risk | 0.959 | |||||||
| No (0) smoking | 44,186 | 44 (0.10) | 314,762 | 0.14 | 1 (reference) | <0.001 | ||
| Light (0.1–19.9) smoking | 13,116 | 20 (0.15) | 93,184 | 0.21 | 1.49 (0.88–2.53) | 0.142 | ||
| Intermediate (20–39.9) smoking | 8103 | 82 (1.01) | 57,352 | 1.43 | 7.90 (5.39–11.56) | <0.001 | ||
| Heavy (≥40) smoking | 3750 | 102 (2.72) | 26,087 | 3.91 | 16.22 (10.97–23.97) | <0.001 | ||
| Intermediate genetic risk | ||||||||
| No (0) smoking | 133,546 | 165 (0.12) | 951,246 | 0.17 | 1 (reference) | <0.001 | ||
| Light (0.1–19.9) smoking | 38,157 | 154 (0.40) | 270,270 | 0.57 | 3.26 (2.61–4.06) | <0.001 | ||
| Intermediate (20–39.9) smoking | 24,437 | 315 (1.29) | 172,743 | 1.82 | 8.32 (6.85–10.11) | <0.001 | ||
| Heavy (≥40) smoking | 11,325 | 385 (3.40) | 78,500 | 4.90 | 17.06 (13.97–20.84) | <0.001 | ||
| High genetic risk | ||||||||
| No (0) smoking | 44,277 | 59 (0.13) | 315,218 | 0.19 | 1 (reference) | <0.001 | ||
| Light (0.1–19.9) smoking | 12,596 | 63 (0.50) | 89,236 | 0.71 | 3.68 (2.58–5.27) | <0.001 | ||
| Intermediate (20–39.9) smoking | 8349 | 130 (1.56) | 58,992 | 2.20 | 9.89 (7.19–13.59) | <0.001 | ||
| Heavy (≥40) smoking | 3952 | 168 (4.25) | 27,325 | 6.15 | 21.22 (15.34–29.35) | <0.001 | ||
IR incidence rate, HR hazard ratio, CI confidence interval.
aIncidence rates are provided per 1000 person-years.
bCox proportional hazards regression adjusted for age, sex, education, Townsend deprivation index, income, BMI, diet, physical activity, alcohol consumption, occupational exposure, passive smoking, relatedness, and first 20 principal components of ancestry. P value for trend calculated treating each smoking category as continuous variables.