Table 2.
Relation between smoking categories and cancer incidence
| Current smoker | |||||
|---|---|---|---|---|---|
| Cancer sites | Never smoker | Former smoker | ≤22 cigarettes/day | >22 cigarettes/day | p-trend |
| All cancers | |||||
| No. of cases, whole cohort (n=5253) | 2965 | 711 | 1272 | 305 | |
| No. of cases, men (n=2741) | 801 | 621 | 1034 | 285 | |
| No. of cases, women (n=2512) | 2164 | 90 | 238 | 20 | |
| Multivariable RR a, whole cohort | 1(Referent) | 1.2 (1.1–1.3) | 1.60 (1.5–1.7) | 1.9 (1.7–2.1) | <0.0001 |
| Multivariable RR a, men | 1 (Referent) | 1.2 (1.1–1.4) | 1.70 (1.6–1.9) | 1.9 (1.7–2.2) | <0.0001 |
| Multivariable RR a, women | 1 (Referent) | 1.3 (1.0–1.6) | 1.45 (1.3–1.7) | 2.1 (1.4–3.3) | <0.0001 |
| Head and neck cancer | |||||
| No. of cases, whole cohort (n=345) | 149 | 48 | 114 | 34 | |
| No. of cases, men (n=252) | 72 | 45 | 104 | 31 | |
| No. of cases, women (n=93) | 77 | 3 | 10 | 3 | |
| Multivariable RR a, whole cohort | 1 (Referent) | 1.2 (0.85–1.7) | 2.1 (1.6–2.71) | 2.5 (1.6–3.7) | <0.0001 |
| Multivariable RR a, men | 1 (Referent) | 1.1 (0.78–1.7) | 2.0 (1.5–2.76) | 2.3 (1.5–3.5) | <0.0001 |
| Multivariable RR a, women | 1 (Referent) | 1.7 (0.54–5.6) | 2.1 (1.1–4.12) | 9.9 (3.1–32.0) | 0.0005 |
| Upper gastrointestinal tract cancer | |||||
| No. of cases, whole cohort (n=458) | 222 | 75 | 127 | 34 | |
| No. of cases, men (n=294) | 83 | 67 | 112 | 32 | |
| No. of cases, women (n=164) | 139 | 8 | 15 | 2 | |
| Multivariable RR a, whole cohort | 1 (Referent) | 1.2 (0.88–1.6) | 1.5 (1.2–1.9) | 1.7 (1.2–2.5) | 0.0004 |
| Multivariable RR a, men | 1 (Referent) | 1.1 (0.82–1.6) | 1.6 (1.2–2.1) | 1.8 (1.2–2.7) | 0.0003 |
| Multivariable RR a, women | 1 (Referent) | 1.6 (0.78–3.3) | 1.1 (0.66–1.9) | 2.7 (0.67–11.01) | 0.26 |
| Colorectal cancer | |||||
| No. of cases, whole cohort (n=931) | 550 | 150 | 201 | 30 | |
| No. of cases, men (n=514) | 185 | 138 | 162 | 29 | |
| No. of cases, women (n=417) | 365 | 12 | 39 | 1 | |
| Multivariable RR a, whole cohort | 1 (Referent) | 1.1 (0.92–1.4) | 1.2 (0.97–1.4) | 0.83 (0.56–1.2) | 0.46 |
| Multivariable RR a, men | 1 (Referent) | 1.2 (0.95–1.5) | 1.2 (0.96–1.5) | 0.87 (0.58–1.3) | 0.47 |
| Multivariable RR a, women | 1 (Referent) | 0.82 (0.46–1.5) | 1.2 (0.84–1.7) | 0.54 (0.08–3.9) | 0.61 |
| Hepatobiliary and pancreas cancer | |||||
| No. of cases, whole cohort (n=480) | 235 | 80 | 136 | 29 | |
| No. of cases, men (n=322) | 107 | 72 | 115 | 28 | |
| No. of cases, women (n=158) | 128 | 8 | 21 | 1 | |
| Multivariable RR a, whole cohort | 1 (Referent) | 1.1 (0.85–1.5) | 1.5 (1.2–1.9) | 1.4 (0.92–2.1) | 0.002 |
| Multivariable RR a, men | 1 (Referent) | 1.1 (0.77–1.4) | 1.4 (1.1–1.8) | 1.3 (0.86–2.0) | 0.02 |
| Multivariable RR a, women | 1 (Referent) | 1.6 (0.79–3.4) | 1.8 (1.1–2.9) | 1.6 (0.22–11.5) | 0.009 |
| Lung cancer | |||||
| No. of cases, whole cohort (n=905) | 254 | 132 | 391 | 128 | |
| No. of cases, men (n=628) | 77 | 110 | 321 | 120 | |
| No. of cases, women (n=277) | 177 | 22 | 70 | 8 | |
| Multivariable RR a, whole cohort | 1 (Referent) | 2.1 (1.6–2.6) | 4.8 (4.0–5.7) | 7.9 (6.2–10.0) | <0.0001 |
| Multivariable RR a, men | 1 (Referent) | 2.0 (1.5–2.7) | 5.0 (3.9–6.4) | 7.9 (5.9–10.6) | <0.0001 |
| Multivariable RR a, women | 1 (Referent) | 2.7 (1.7–4.3) | 4.3 (3.2–5.7) | 8.3 (4.0–17.1) | <0.0001 |
| Bladder/renal pelvis cancer | |||||
| No. of cases, whole cohort (n=146) | 61 | 33 | 40 | 12 | |
| Multivariable RR a, whole cohort | 1 (Referent) | 1.5 (0.96–2.5) | 1.7 (1.1–2.7) | 2.7 (1.4–5.2) | 0.002 |
| Breast cancer (women only) | |||||
| No. of cases, women (n=534) | 491 | 14 | 28 | 1 | |
| Multivariable RR a, women | 1 (Referent) | 1.2 (0.68–2.0) | 0.97 (0.66–1.4) | 0.58 (0.08–4.1) | 0.87 |
a
Relative risk (95% confidence interval) estimated from a multivariable-adjusted proportional hazards model adjusted for age (years), gender (males, females), dialect group (Cantonese, Hokkien), year of recruitment, level of education (no formal education, primary school, secondary school or above), daily ethanol intake (g), and h/week of moderate physical activity (none, ½ to 3 h/week, 4 h/week or more).