Table 2. The HR with 95% CI for the association of changes in CC and NNTP use habits with overall cancer risk according to subgroups of age and sex

Parameter N (%) Events Person–years IR* HR (95% CI)
Model 1 Model 2 Model 3
Male, aged ≥40
Continual CC–only smokers 482,771 12,759 1,393,617 9.2 1.62 (1.57–1.66) 1.69 (1.64–1.73) 1.64 (1.59–1.68) 1.0 (ref)
CC and NNTP users 52,666 676 151,828 4.5 1.38 (1.27–1.49) 1.45 (1.34–1.57) 1.41 (1.30–1.52) 0.86 (0.79–0.93)
Recent (<5 y) CC quitters 103,007 3,042 300,423 10.1 1.53 (1.47–1.59) 1.56 (1.50–1.63) 1.51 (1.45–1.58) 0.92 (0.87–0.97)
Long–term (≥5 y) CC quitters without NNTP use 430,641 12,290 1,275,574 9.6 1.20 (1.17–1.24) 1.24 (1.20–1.27) 1.21 (1.18–1.24) 0.74 (0.71–0.77)
Long–term (≥5 y) CC quitters with NNTP use 1,956 21 5,041 4.2 1.15 (0.75–1.76) 1.17 (0.76–1.80) 1.14 (0.74–1.75) 0.70 (0.45–1.07)
Never smokers 399,332 10,579 1,171,591 9.0 1.0 (ref) 1.0 (ref) 1.0 (ref) 0.61 (0.59–0.63)
Male, aged <40
Continual CC–only smokers 161,148 595 491,802 1.2 0.84 (0.76–0.94) 0.91 (0.81–1.01) 0.92 (0.80–1.06) 1.0 (ref)
CC and NNTP users 44,083 216 133,120 1.6 1.09 (0.94–1.27) 1.13 (0.97–1.32) 1.16 (0.97–1.38) 1.26 (1.00–1.58)
Recent (<5 y) CC quitters 31,779 158 96,888 1.6 1.09 (0.92–1.29) 1.14 (0.96–1.36) 1.16 (0.96–1.40) 1.26 (1.00–1.60)
Long–term (≥5 y) CC quitters without NNTP use 54,079 301 169,955 1.8 1.10 (0.96–1.25) 1.15 (1.00–1.32) 1.17 (1.00–1.35) 1.27 (1.04–1.56)
Long–term (≥5 y) CC quitters with NNTP use 1,511 4 4,044 1.0 0.67 (0.25–1.79) 0.70 (0.26–1.87) 0.71 (0.27–1.91) 0.77 (0.29–2.07)
Never smokers 204,083 850 624,272 1.4 1.0 (ref) 1.0 (ref) 1.0 (ref) 1.09 (0.94–1.25)
Female, aged ≥40
Continual CC–only smokers 37,372 954 103,617 9.2 1.22 (1.14–1.30) 1.33 (1.25–1.42) 1.26 (1.17–1.35) 1.0 (ref)
CC and NNTP users 2,413 48 6,358 7.5 1.13 (0.85–1.50) 1.25 (0.94–1.66) 1.20 (0.90–1.59) 0.95 (0.71–1.28)
Recent (<5 y) CC quitters 8,357 211 23,438 9.0 1.20 (1.05–1.37) 1.27 (1.11–1.46) 1.22 (1.06–1.39) 0.97 (0.83–1.13)
Long–term (≥5 y) CC quitters without NNTP use 15,217 359 42,493 8.4 1.17 (1.05–1.30) 1.24 (1.12–1.38) 1.20 (1.08–1.34) 0.95 (0.84–1.08)
Long–term (≥5 y) CC quitters with NNTP use 184 1 419 2.4 0.37 (0.05–2.62) 0.40 (0.06–2.81) 0.38 (0.05–2.72) 0.30 (0.04–2.23)
Never smokers 1,766,610 41,973 508,2480 8.3 1.0 (ref) 1.0 (ref) 1.0 (ref) 0.79 (0.74–0.85)
Female, aged <40
Continual CC–only smokers 11,188 78 31,561 2.5 0.87 (0.70–1.09) 0.91 (0.73–1.14) 0.88 (0.68–1.14) 1.0 (ref)
CC and NNTP users 2,589 18 6,882 2.6 0.91 (0.58–1.45) 0.95 (0.60–1.52) 0.92 (0.57–1.49) 1.05 (0.61–1.80)
Recent (<5 y) CC quitters 3,950 27 10,721 2.5 0.85 (0.58–1.24) 0.89 (0.61–1.29) 0.86 (0.58–1.27) 0.98 (0.61–1.56)
Long–term (≥5 y) CC quitters without NNTP use 6,421 74 17,786 4.2 1.29 (1.02–1.62) 1.35 (1.07–1.70) 1.32 (1.04–1.68) 1.50 (1.05–2.13)
Long–term (≥5 y) CC quitters with NNTP use 250 2 565 3.5 1.19 (0.30–4.76) 1.27 (0.32–5.08) 1.24 (0.31–4.96) 1.41 (0.34–5.77)
Never smokers 365,950 3,187 1,031,750 3.1 1.0 (ref) 1.0 (ref) 1.0 (ref) 1.14 (0.88–1.47)
Abbreviation: CC, combustible cigarette; CI, confidence interval; HR, hazard ratio; IR, indicate rate; NNTP, noncombustible nicotine or tobacco product.
Incidence rate expressed as per 1000 person-years.
Model 1: adjusted for age (20–39, 40–59, and ≥60 years) and sex.
Model 2: adjusted for age (20–39, 40–59, and ≥60 years); sex; household income (low income, middle income, and high income); region of residence (urban and rural); Charlson comorbidity index (0, 1, and ≥2); body mass index (<25 kg/m2, 25–30 kg/m2, and ≥30 kg/m2); systolic blood pressure; diastolic blood pressure; fasting blood glucose; serum total cholesterol; alcohol consumption (<1 times per week, 1–3 times per week, and ≥4 times per week); exercise (sufficient and non-sufficient).
Model 3: adjusted for age (20–39, 40–59, and ≥60 years); sex; household income (low income, middle income, and high income); region of residence (urban and rural); Charlson comorbidity index (0, 1, and ≥2); body mass index (<25 kg/m2, 25–30 kg/m2, and ≥30 kg/m2); systolic blood pressure; diastolic blood pressure; fasting blood glucose; serum total cholesterol; alcohol consumption (<1 times per week, 1–3 times per week, and ≥4 times per week); exercise (sufficient and non-sufficient); pack–years of smoking.
Numbers in bold indicate a significant difference (P<0.05).