Cannabis smoking and risk of lung cancer in men: a pooled analysis of three studies in Maghreb.

BACKGROUND: Cannabis is the most widely consumed illicit drug worldwide and the relation between cannabis smoking and lung cancer is suggestive, albeit inconclusive. METHOD: We conducted three hospital based case-control studies in Tunisia, Morocco, and Algeria, three areas of high prevalence of cannabis consumption as well as production. This paper presents the pooled analysis of these three studies restricted to men with a total of 430 cases and 778 controls. RESULTS: Ninety-six percent of the cases and 67.8% of the controls were tobacco smokers and 15.3% of the cases and 5% of the controls were ever cannabis smokers. All cannabis smokers were tobacco users. Adjusting for country, age, tobacco smoking, and occupational exposure, the odds ratio (OR) for lung cancer was 2.4 (95% confidence interval [CI]: 1.6-3.8) for ever cannabis smoking. This association remained after adjustment for lifetime tobacco packyears as continuous variable, OR = 2.3 (95% CI: 1.5-3.6). The OR adjusted for intensity of tobacco smoking (cigarette/d) among current tobacco smokers and never cannabis smokers was 10.9 (95% CI: 6.0-19.7) and the OR among current tobacco users and ever cannabis smokers was 18.2 (95% CI: 8.0-41.0). The risk of lung cancer increased with increasing joint-years, but not with increasing dose or duration of cannabis smoking. CONCLUSION: Our results suggest that cannabis smoking may be a risk factor for lung cancer. However, residual confounding by tobacco smoking or other potential confounders may explain part of the increased risk.

A case-control study of lung cancer in Casablanca, Morocco.

OBJECTIVE: To evaluate etiologic risk factors for lung cancer in Casablanca, Morocco. METHODS: We conducted a hospital-based case-control study that included 118 incident lung cancer cases and 235 age-, sex- and residence-matched controls. We analyzed the data using matched univariate and matched and unmatched multivariate logistic regression analyses. RESULTS: Active tobacco smoking and history of chronic bronchitis were the strongest risk factors for lung cancer in the matched logistic regression model. Multivariate odds ratio (OR) and 95% confidence intervals varied from 1.79 (0.47-6.79) for former light smokers to 26.07 (6.58-103.27) for current heavy tobacco smokers at the time of disease occurrence. Combined use of hashish/kiff and snuff had an OR of 6.67 (1.65-26.90), whereas the OR for hashish/kiff (without snuff) was 1.93 (0.57-6.58). History of chronic bronchitis had an OR of 4.16 (1.76-9.85). Other slightly increased risks of lung cancer were found for exposure to passive smoking (1.36; 0.71-2.62), occupational exposures (1.75; 0.84-3.63), use of candles for lighting (1.44; 0.42-5.01), and poor ventilation of the kitchen (1.22; 0.57-2.58). CONCLUSIONS: This study confirms known risk factors for lung cancer and uncovers potential new etiologic ones such as the role of hashish/kiff.