Table 3

Lung cancer risk in current smokers in relation to smoking duration, cpd, and age at onset of smoking habit

United StatesJapan
CasesHospital ControlsOR (95% CI)CasesHospital ControlsCommunity ControlsOR (95% CI) (HC; CC)a
n 14839284115160
Smoking duration (yr) %
 ≤4038.556.425.2 (11.9–61.0)b40.571.345.02.2 (1.1–5.2); 4.8 (2.6–8.9)c
 >4061.543.657.8 (27.4–131.9)b59.528.755.07.4 (2.9–19.4); 8.3 (4.5–15.4)c
 Mean (SD)42.6 (10.8)38.7 (12.3)41.6 (9.8)35.4 (9.8)40.6 (10.3)
cpd %
 <2010.838.510.9 (4.4–28.0)b16.829.830.61.6 (0.7–3.9); 2.6 (1.4–4.9)c
 20–2935.128.253.4 (23.1–135.2)b35.034.241.33.5 (1.5–8.4); 4.3 (2.4–7.6)c
 ≥3054.133.373.3 (32.5–181.6)b48.236.028.16.2 (2.6–15.0); 9.3 (5.2–16.7)c,d
 Mean (SD)30.6 (15.5)22.9 (16.4)29.5 (15)25 (14.8)22.7 (12.8)
Age at onset of smoking (yr) %
 <1430.420.51.2 (0.4–3.4)e0.70.00.0(f)
 15–1738.533.31 (reference)e21.111.315.61 (reference)g
 18–2018.225.60.6 (0.2–1.7)e61.668.760.00.2 (0.1–0.6); 0.8 (0.5–1.3)g
 >2012.820.50.5 (0.2–1.4)e16.620.024.40.2 (0.1–0.8); 0.5 (0.3–0.9)g,h
 Mean (SD)16.8 (5.8)17.8 (5.0)19.3 (2.9)20.2 (4.7)20.5 (5.8)
  • a HC, hospital controls; CC, community controls.

  • b Adjusted for age, education, and hospital; reference group is nonsmokers.

  • c Adjusted for age and education; reference group is nonsmokers.

  • d P < 0.001, test for linear trend.

  • e Adjusted for age, education and hospital; reference group is 15–17 yrs.

  • f ORs were not computed because no current smokers started smoking before the age of 15 in Japanese controls.

  • g Adjusted for age and education; reference group is 15–17 yrs.

  • h P < 0.01, test for linear trend.