Table 2.

Relative risk of lung cancer death by pack‐years among current smokers, Three‐Prefecture Cohort Study, Japan

Pack‐years of smoking	No. subjects	Person‐years	No. lung cancer deaths	Crude death rate	Relative risk † (95%CI)
Men ‡
<20	3 982	33 592	19	56.6	1.16 (0.72–1.88)
20–39	12 066	101 910	113	110.9	2.10 (1.62–2.71)
40–59	6 574	54 374	129	237.2	2.86 (2.23–3.65)
60 +	2 765	22 770	78	342.6	4.44 (3.34–5.89)
P for trend					<0.0001
Women §
<20	3 136	26 212	12	45.8	1.75 (0.96–3.19)
20–39	1 545	12 642	15	118.7	3.92 (2.27–6.76)
40 +	397	3 157	10	316.8	7.22 (3.75–13.9)
P for trend					<0.0001

^† Adjusted for age and prefecture. Reference category was non‐smokers.

^{‡ ‡} 310 men were excluded because of missing data.

^{§ §} 110 women were excluded because of missing data.