A case-control study published in the Journal of Oncology Research and Therapy found that individuals who smoked combustible cigarettes and used e-cigarettes (vaped) in tandem had a substantially higher risk of developing lung cancer compared to those who only smoked cigarettes. The research, conducted by researchers from The Ohio State University, suggested that adding vaping to cigarette smoking may accelerate lung cancer development.

Methods

The researchers analyzed the medical records of 4,975 pathologically confirmed lung cancer cases and 27,294 cancer-free controls matched on age, gender, race, and location. Logistic regression was used to estimate odds ratios adjusted for age, gender, race, chronic obstructive pulmonary disease, and coronary artery disease. The mean patient age was 62 years; 54.6% of participants were male and 45.4% were female; and 88.5% of participants were White, while 11.2% were Black.

Key Findings

Individuals who both vaped and smoked cigarettes had three- to fourfold higher odds of developing lung cancer compared to those who only smoked cigarettes.

The adjusted odds ratio (OR) for combined vaping and smoking was 38.7 (95% confidence interval [CI], 31.5-47.6) versus 9.6 (95% CI, 8.7-10.6) for smoking alone. This elevated risk persisted across gender, histological subtypes of lung cancer, and cumulative smoking history.

Among the cohort, 89.3% of lung cancer cases reported smoking versus 37.6% of controls, 6.3% of cases reported vaping versus 0.80% of controls, and over 97% of vapers also reported smoking.

Odds ratios for the development of lung cancer by smoking/vaping status were 57.8 (95% CI, 47.4-70.5) for both methods together and 13.9 for smoking alone (95% CI, 12.7-15.3). Adjusted odds ratios accounting for comorbidities were 38.7 (95% CI, 31.5-47.6) for vaping and smoking and 9.6 (95% CI, 8.7-10.6) for smoking alone.

Lung cancer risk by histological subtype was as follows:

• Adenocarcinoma: OR = 20.2 (95% CI, 15.7-26.0) for vaping and smoking vs OR = 4.7 (95% CI, 4.2-5.4) for smoking alone
• Squamous cell carcinoma: OR = 46.0 (95% CI, 32.9-64.3) for vaping and smoking vs OR = 10.8 (95% CI, 8.8-13.4) for smoking alone.

By cumulative smoking history, lung cancer risk was:

• ≥ 40 pack-years: OR = 68.1 (95% CI, 51.4-90.8) for vaping and smoking vs OR = 19.8 (95% CI, 17.9-21.0) for smoking alone
• < 40 pack-years: OR = 30.9 (95% CI, 23.5-40.5) for vaping and smoking vs OR = 8.8 (95% CI, 7.9-9.8) for smoking alone.

The study authors hypothesized that the addition of e-cigarette use by chronic cigarette smokers may have increased rather than decreased exposure to certain lung carcinogens, potentially explaining the elevated risk associated with both methods used in tandem.

The researchers noted that they were unable to quantify vaping levels or timing relative to smoking cessation. Additionally, the study design did not allow for assessment of lung cancer risk from vaping alone without concurrent cigarette smoking.

This large case-control study provided evidence that dual use of e-cigarettes and combustible cigarettes was associated with a significantly higher risk of lung cancer compared to cigarette smoking alone. The authors called for well-designed prospective studies to further examine the carcinogenic potential of electronic nicotine delivery systems, particularly given the high prevalence of vaping among youth at the time of the study.

The authors declared that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.