TABLE 2 ] .

Epidemiologic Studies of Cannabis Association With Lung Cancer

Study Type	Cohort Size, Location, Racial Features	Subjects With Cancer and Control Subjects	How Cannabis Use Assessed and Quantitateda	Approximate Cannabis Use Among Cannabis Smokers	Years of Cannabis Use	Main Findings and Observations	Reference
Case-control cohort	403 New Zealand residents	79 lung cancer 324 control	Duration of cannabis use, joint-y, pack-y tobacco use	12 of 79 cases with > 10.5 joint-y compared with four of 324 control subjects	2001-2005	After adjustment for family history and pack-y tobacco, relative risk for lung cancer was 1.08 (95% CI, 1.02-1.15) per joint-y cannabis smoking	16
Cross-sectional	29,195 National surveys on drug use and health, United States Adjusted for race/ethnicity	Lung cancer by duration of cannabis use: Never = 9 ≤ 1 y = 23 2-10 y = 23 ≥ 11 y = 67	Duration of cannabis use (y); daily tobacco use also ascertained for use in models	Not reported	2005-2007	After adjustment, cannabis use of ≥ 11 y associated with OR for lung cancer development of 7.87 (95% CI, 1.28-48.4)	18
Longitudinal evaluation over 40 y of single cohort	49,321 Swedish men born in 1949-1951 conscripted in 1969-1970 for military service	189 lung cancer 49,132 control	Ever or never use of cannabis, lifetime frequency of cannabis use, No. tobacco cigarettes per day	5,156 ever cannabis users 831 of 5,156 (16%) reported > 50 times of use 515 of 831 (62%) also smoked > 10 cigarettes/d	1969-2009	After adjusting for tobacco and alcohol consumption, smoking cannabis > 50 times was associated with a hazard ratio of 2.12 (95% CI, 1.08-4.14) for lung cancer development over 40 y; ever use was not associated with an increased hazard ratio for lung cancer	17
Analysis of pooled data from six case-control studies	5,144 International Lung Cancer Consortium: United States, Europe, New Zealand 79% white, 11% black	2,159 lung cancer 2,985 control	Lifetime cannabis use, joint-y; 86% of habitual cigarette smokers also used cannabis	10% of patients with lung cancer were habitual cannabis users 6% with ≥ 10 joint-y	1999-2013	Little or no association between intensity, duration, or cumulative use of cannabis and risk of lung cancer development; pooled OR for association between cannabis smoking (habitual vs nonhabitual) and lung cancer risk was 0.95 (95% CI, 0.66-1.38)	19

^aPack-y = 1 pack/d tobacco cigarettes × 20 cigarettes/pack × 365 d/y; joint-y = 1 joint/d × 365 d/y.