Introduction: Risk of lung cancer is often reported as elevated for patients with cryptogenic fibrosing alveolitis (CFA).
Methods: Vital status was sought for all 588 members of the British Thoracic Society (BTS) cryptogenic fibrosing alveolitis (CFA) study eleven years after entry to the cohort. Observed deaths due to lung cancer were compared to expected, using age-, sex- and period-adjusted national rates. The roles of reported asbestos exposure and smoking were also investigated.
Results: 488 (83%) cohort members had died; 46 (9%) were certified to lung cancer (ICD9 162). The standardised mortality ratio (SMR) was 7.4 (95% ci [5.4, 9.9]). Stratified analysis demonstrated increased lung cancer mortality amongst younger subjects, males and ever smokers. Using an independent expert panel, 25 (4%) cohort members were considered to have at least moderate exposure to asbestos; lung cancer risk was elevated for these subjects (SMR 13.1 [3.6, 33.6]) versus 7.2 (5.2, 9.7) for those with less, or no, asbestos exposure. Ever smoking was reported by 448 (73%) of the cohort and was considerably higher in males (92%) than females (49%); p<0.001. Most (87%) lung cancer decedents were male and all but two (96%) lung cancer decedents ever smoked. Ever smokers presented at a younger age (mean 67 versus 70 years; p<0.001) and with less breathlessness (12% smokers reported no breathlessness versus 5% never smokers; p=0.02).
Discussion: These findings confirm an association between CFA and lung cancer although this relationship may not be causal. The high rate of smoking, and evidence that smokers present for medical attention earlier than non-smokers, suggest that smoking could be confounding this association.