Associations Between Smoking Illicit Drugs and Lung and Upper Aerodigestive Tract Cancers: A Case-Control Study in Los Angeles County

Introduction: The global epidemic of illicit drug use raises questions about the potential increased risk of tobacco-related cancers associated with drug smoking.

Objectives: This study aimed to investigate potential associations between smoking three specific drugs - opium, phencyclidine (PCP), and crack cocaine - and the development of lung and upper aerodigestive tract (UADT) cancers.

Methods: A population-based case-control study was conducted in Los Angeles County from 1999 to 2004. The study included 611 lung cancer cases (50% male), 601 UADT cancer cases (76% male), and 1,040 controls (60% male). Face-to-face interviews were conducted to collect epidemiological data, including drug smoking histories. Logistic regressions were used to estimate associations.

Results: After adjusting for potential confounders, it was found that ever smoking crack cocaine was positively associated with UADT cancers (adjusted odds ratio [aOR] = 1.56, 95% confidence interval [CI]: 1.05, 2.33). A dose-response relationship was observed between crack smoking frequency and UADT cancers (p for trend = .024). Heavy (> median) crack smoking was associated with both UADT cancers (aOR = 1.81, 95% CI: 1.07, 3.08) and lung cancer (aOR = 1.58, 95% CI: 0.88, 2.83). A positive association was also observed between heavy PCP smoking and UADT cancers (aOR = 2.29, 95% CI: 0.91, 5.79). However, little to no associations were found between opium smoking and lung or UADT cancers.

Conclusion: The findings suggest that smoking illicit drugs, specifically crack cocaine and PCP, may increase the risk of developing tobacco-related cancers such as lung and UADT cancers. Despite the low frequency of drug smoking and potential residual confounding, these results provide valuable insights into the development of lung and UADT cancers.