Is smoking marijuana safer than smoking cigars and cigarettes in terms of lung cancer risk?

Smoking Marijuana vs. Cigars and Cigarettes: Lung Cancer Risk Comparison

Based on current evidence, smoking marijuana appears to pose less risk for lung cancer than smoking cigars and cigarettes, though marijuana smoking is not risk-free and may still be associated with lung cancer, particularly with heavy use.

Tobacco Products and Lung Cancer Risk

Cigarette Smoking

• Cigarette smoking is the predominant cause of lung cancer and accounts for approximately 85% of all lung cancer-related deaths 1
• The relative risk for lung cancer is approximately 20-fold higher for cigarette smokers compared to nonsmokers 1
• All four major types of lung cancer (adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and small cell carcinoma) are caused by cigarette smoking 1
• A clear dose-response relationship exists between tobacco smoking and lung cancer risk 1

Cigar Smoking

• Cigar smoking is an established cause of lung cancer 1
• The lung cancer risks from cigar smoking are substantial but less than cigarette smoking due to differences in smoking frequency and depth of inhalation 1
• Similar pattern applies to pipe smoking 1

Marijuana Smoking and Lung Cancer Risk

Current Evidence

• According to the American College of Chest Physicians guidelines, "despite the plausibility of marijuana as a risk factor for lung cancer, the evidence to date has not documented an association after adjusting for tobacco smoking" 1
• Cannabis smoke contains many of the same carcinogens as tobacco smoke, raising theoretical concerns 2, 3, 4

Research Findings

• A 40-year cohort study found that "heavy" cannabis smoking (>50 times lifetime use) was associated with a twofold increased risk of developing lung cancer (HR 2.12,95% CI 1.08-4.14), even after adjusting for tobacco use 2
• A 2018 review noted that "a large cohort study and a pooled analysis of six well-designed case-control studies have not found evidence of a link between marijuana smoking and lung cancer" 3
• A 2018 review stated that "smoking cannabis has not been proved to be a risk factor in the development of lung cancer, but the data are limited" 4
• A recent study (2025) found that cannabis smokers were diagnosed with lung cancer at a significantly younger age than tobacco-only smokers (mean 52.9 vs 67.7 years) 5

Health Effects of Marijuana Smoking

Respiratory Effects

• Smoking cannabis may affect lung function and is associated with chronic bronchitis and COPD 1
• Marijuana smoking shows significant association with chronic bronchitis symptoms 3
• Bronchial biopsies from habitual marijuana smokers have shown precancerous histopathologic changes 3
• Few studies have found a relationship between marijuana smoking and decreased FEV1/FVC ratio 3
• Diffusing capacity in marijuana smokers has been normal, and studies have not shown association with emphysema 3

Other Health Concerns

• Mental health problems are among possible effects in long-term cannabis users 1
• Cannabis smoking may be associated with adverse cardiovascular events, including myocardial infarction and stroke 1
• High doses of THC may be associated with psychosis 1
• Cannabis potency has increased significantly in recent decades (average THC concentration nearly doubled from 9% in 2008 to 17% in 2017) 1

Comparative Risk Assessment

Key Differences

• Tobacco smoking has a well-established, strong causal relationship with lung cancer
• Marijuana smoking has a less clear relationship with lung cancer, with mixed evidence
• Differences in typical usage patterns (frequency, depth of inhalation, filter use) may contribute to different risk profiles

Confounding Factors

• Many marijuana users also smoke tobacco, making it difficult to isolate the effects of marijuana alone
• Studies are limited by small sample sizes, self-reporting biases, and confounding factors 4
• Cannabis potency and consumption methods have changed over time, potentially affecting risk profiles

Clinical Implications

• Smoking cessation of all forms (tobacco and marijuana) should be encouraged for optimal lung health
• Patients who use marijuana should be informed about potential respiratory risks, even if the lung cancer risk appears lower than with tobacco
• Alternative delivery methods (edibles, vaporizers) may reduce respiratory risks but carry their own potential health concerns
• Regular screening for those at high risk for lung cancer should follow established guidelines based primarily on tobacco smoking history

Caveats and Limitations

• Research on marijuana's long-term effects is limited by its historical illegal status
• Most studies have methodological limitations including small sample sizes and confounding factors
• The increasing potency of modern cannabis may not be reflected in older studies
• Different consumption methods (joints, pipes, vaporizers) may have different risk profiles

While marijuana smoking appears to pose less lung cancer risk than tobacco products, it is not risk-free, and heavy, long-term use may still increase lung cancer risk. The evidence suggests a more cautious approach than considering marijuana smoking "safe" from a pulmonary perspective.