• The University of Auckland Faculty of Medical and Health Sciences, Auckland, New Zealand.
• Department of Biostatistics and Centre for Statistical Science, Brown University, Providence, Rhode Island, USA.
• Department of Radiology, Wake Forest Baptist Medical Comprehensive Cancer Center, Winston-Salem, North Carolina, USA.
• Natera Inc, Berkeley, California, USA.
• Department of Radiological Sciences, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA.
• The University of Auckland Faculty of Medical and Health Sciences, Auckland, New Zealand roberty@adhb.govt.nz.

IMPORTANCE: While cholinergic receptor nicotinic alpha 5 (CHRNA5) variants have been linked to lung cancer, chronic obstructive pulmonary disease (COPD) and smoking addiction in case-controls studies, their corelationship is not well understood and requires retesting in a cohort study.

OBJECTIVE: To re-examine the association between the CHRNA5 variant (rs16969968 AA genotype) and the development of lung cancer, relative to its association with COPD and smoking.

METHODS: In 9270 Non-Hispanic white subjects from the National Lung Screening Trial, a substudy of high-risk smokers were followed for an average of 6.4 years. We compared CHRNA5 genotype according to baseline smoking exposure, lung function and COPD status. We also compared the lung cancer incidence rate, and used multiple logistic regression and mediation analysis to examine the role of the AA genotype of the CHRNA5 variant in smoking exposure, COPD and lung cancer.

RESULTS: As previously reported, we found the AA high-risk genotype was associated with lower lung function (p=0.005), greater smoking intensity (p<0.001), the presence of COPD (OR 1.28 (95% CI 1.10 to 1.49) p=0.0015) and the development of lung cancer (HR 1.41, (95% CI 1.03 to 1.93) p=0.03). In a mediation analyses, the AA genotype was independently associated with smoking intensity (OR 1.42 (95% CI 1.25 to 1.60, p<0.0001), COPD (OR 1.25, (95% CI 1.66 to 2.53), p=0.0015) and developing lung cancer (OR 1.37, (95% CI 1.03 to 1.82) p=0.03).

CONCLUSION: In this large-prospective study, we found the CHRNA5 rs 16 969 968 AA genotype to be independently associated with smoking exposure, COPD and lung cancer (triple whammy effect).