Table 3. Odds-ratio estimates for the association between Cannabis smoking characteristics and lung cancer, results for all lung cancer.
| Cannabis smoking characteristics | All subjects | Never tobacco smokers | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cases (n = 2,159) | Controls (n = 2,985) | No. of studies | Pooled OR1 (95% Cl) | Het (P) | I2 | Cases (n = 370) | Controls (n = 1,358) | OR (95% CI)2 | |||||
| No. | % | No. | % | No. | % | No. | % | ||||||
| Status3 | |||||||||||||
| Nonhabitual smoker4 | 1,934 | (90) | 2,664 | (89) | 1.00 (Ref) | 359 | (97.0) | 1294 | (95.3) | 1.00 | |||
| Habitual | 225 | (10) | 321 | (11) | 6 | 0.96 (0.66-1.38) | 0.17 | 35.38 | 11 | (3.0) | 64 | (4.7) | 1.03 (0.51-2.08) |
| Intensity (joints/day)3 | |||||||||||||
| Nonhabitual smoker4 | 1,934 | (90) | 2,664 | (89) | 1.00 (Ref) | 359 | (97.0) | 1294 | (95.3) | 1.00 | |||
| <1 | 96 | (4) | 178 | (6) | 5 | 0.77 (0.51-1.16) | 0.32 | 15.51 | 9 | (2.4) | 41 | (3.0) | 1.33 (0.61-2.93) |
| ≥1 | 126 | (6) | 133 | (5) | 4 | 0.88(0.63-1.24)5 | 0.86 | 0.00 | 2 | (0.5) | 23 | (1.7) | 0.49 (0.11-2.25) |
| Continuous | 6 | 1.02 (0.92-1.13) | 0.28 | 20.82 | 1.08 (0.91-1.30) | ||||||||
| Duration, years3 | |||||||||||||
| Nonhabitual smoker4 | 1,934 | (90) | 2,664 | (89) | 1.00 (Ref) | 359 | (97.0) | 1294 | (95.3) | 1.00 | |||
| >0-<20 | 149 | (7) | 226 | (8) | 6 | 0.94 (0.70-1.26) | 0.40 | 2.35 | 8 | (2.2) | 49 | (3.6) | 0.89 (0.39-2.00) |
| ≥20 | 76 | (3) | 95 | (3) | 5 | 1.03 (054-1.98) | 0.07 | 53.21 | 3 | (0.8) | 15 | (1.1) | 1.64 (0.45-6.00) |
| Continuous | 3 | 0.99 (0.97-1.02)6 | 0.27 | 23.01 | 0.97 (0.93-1.01) | ||||||||
| Joint-years3 | |||||||||||||
| Nonhabitual smoker (<1)4 | 1,934 | (90) | 2,664 | (90) | 1.00 (Ref) | 359 | (97.0) | 1294 | (95.3) | 1.00 | |||
| 1-<10 | 94 | (4) | 180 | (6) | 5 | 0.69 (0.41-1.17) | 0.21 | 31.95 | 9 | (2.4) | 44 | (3.2) | 1.26 (0.57-2.75) |
| ≥10 | 128 | (6) | 132 | (4) | 4 | 0.94(0.67-1.32)7 | 0.62 | 0.00 | 2 | (0.5) | 20 | (1.5) | 0.54 (0.12-2.55) |
| Continuous | 5 | 1.00(0.99-1.00)8 | 0.61 | 0.00 | 1.00 (0.93-1.07) | ||||||||
| Age of start, years3 | |||||||||||||
| Nonhabitual smoker4 | 1,934 | (90) | 2,664 | (90) | 1.00 (Ref) | 359 | (97.0) | 1294 | (95.3) | 1.00 | |||
| >18 | 86 | (4) | 127 | (4) | 4 | 0.75 (0.53-1.08) | 0.45 | 0.00 | 6 | (1.6) | 28 | (2.1) | 1.25 (0.47-3.29) |
| ≤18 | 124 | (6) | 187 | (6) | 3 | 0.86(0.62-1.19)9 | 0.67 | 0.00 | 5 | (1.4) | 36 | (2.6) | 0.85 (0.32-2.31) |
Random effect model.
Adjusted for age, sex, race, highest education, and study.
Study-specific models were adjusted for age, sex, race, highest education, tobacco smoking status and tobacco smoking pack-years. Exceptions are models for continuous variables for Moffitt Cancer Study and Memorial Sloan-Kettering Cancer Center Study, which were adjusted for age, sex, and tobacco smoking pack-years as the base.
Nonhabitual cannabis smoker is defined as those with cumulative cannabis consumption of less than 1 joint-year (equivalent of 1 joint per day for 1 year), including never users.
Summary OR based on 4 studies excluding New Zealand (OR=7.16, 95%CI 2.07-24.78), P-value for heterogeneity when it is included = 0.03.
Summary OR based on 3 studies excluding Moffitt Cancer Study (OR=1.16,95%CI 1.01-1.33), MSH-PMH Study (OR=0.97, 95%CI 0.97-0.99) and New Zealand (OR=1.05, 95%CI 1.01-1.09), P-value for heterogeneity when they are included < 0.001.
Summary OR based on 4 studies excluding New Zealand (OR=7.39, 95%CI 2.37-23.04), P-value for heterogeneity when it is included = 0.01.
Summary OR based on 5 studies excluding New Zealand (OR=1.09, 95%CI 1.03-1.16), P-value for heterogeneity when it is included = 0.03.
Summary OR based on 3 studies excluding New Zealand (OR=0.93, 95%CI 0.79-1.09), P-value for heterogeneity when it is included = 0.02.
Abbreviations: CI, confidence interval; Het, heterogeneity; No., number.