White Blood Cell Count and Risk of Incident Lung Cancer in the UK Biobank.

Abstract

The contribution of measurable immunological and inflammatory parameters to lung cancer development remains unclear, particularly among never smokers. We investigated the relationship between total and differential white blood cell (WBC) counts and incident lung cancer risk overall and among subgroups defined by smoking status and sex in the United Kingdom (UK). We evaluated 424 407 adults aged 37-73 years from the UK Biobank. Questionnaires, physical measurements, and blood were administered and collected at baseline in 2006-2010. Complete blood cell counts were measured using standard methods. Lung cancer diagnoses and histological classifications were obtained from cancer registries. Multivariable Cox regression models were used to estimate the hazard ratio (HR) and 95% confidence intervals of incident lung cancer in relation to quartiles (Q) of total WBC and subtype-specific counts, with Q1 as the reference. There were 1493 incident cases diagnosed over an average 7-year follow-up. Overall, the highest quartile of total WBC count was statistically significantly associated with elevated lung cancer risk (HRQ4 = 1.67, 95% CI = 1.41 to 1.98). Among women, increased risks were found in current smokers (n cases / n = 244 / 19 464, HRQ4 = 2.15, 95% CI = 1.46 to 3.16), former smokers (n cases / n = 280 / 69 198, HRQ4 = 1.75, 95% CI = 1.24 to 2.47), and never smokers without environmental tobacco smoke exposure (ncases / n = 108 / 111 294, HRQ4 = 1.93, 95% CI = 1.11 to 3.35). Among men, stronger associations were identified in current smokers (ncase s / n = 329 / 22 934, HRQ4 = 2.95, 95% CI = 2.04 to 4.26) and former smokers (nc ases / n = 358/71 616, HRQ4 = 2.38, 95% CI = 1.74 to 3.27) but not in never smokers. Findings were similar for lung adenocarcinoma and squamous cell carcinoma and were driven primarily by elevated neutrophil fractions. Elevated WBCs could potentially be one of many important markers for increased lung cancer risk, especially among never-smoking women and ever-smoking men.