Lung cancer and cryptogenic fibrosing alveolitis - A population-based cohort study

Cryptogenic fibrosing alveolitis has been reported to be associated with an increased risk of lung cancer. However, it has recently become apparent th at cigarette smoking may be a risk factor for cryptogenic fibrosing alveoli tis as well as for lung cancer, and so may confound the association between these conditions. We have therefore estimated the independent increase in lung cancer incidence in patients with cryptogenic fibrosing alveolitis com pared with the general population in a population-based cohort study involv ing 890 subjects with cryptogenic fibrosing alveolitis and 5,884 control su bjects drawn from the United Kingdom General Practice Research Database. Th e incidence of lung cancer was markedly increased among patients with crypt ogenic fibrosing alveolitis (rate ratio [RR] 7.31, 95% confidence interval [95% CI] 4.47 to 11.93, p < 0.001), and adjustment for previous smoking his tory had little effect on this odds ratio (adjusted RR: 8.25, 95% CI 4.70 t o 11.48, p < 0.001). This increase in lung cancer incidence remained when t he analysis was restricted to current smokers (RR 7.36, 95% CI 1.54 to 35.1 9, p = 0.012). This study provides clear evidence that the incidence of lun g cancer is increased in patients with cryptogenic fibrosing alveolitis, an d that this effect is independent of the effect of cigarette smoking.