The effects of pulmonary diseases on histologic types of lung cancer in both sexes: a population-based study in Taiwan.

BACKGROUND: The associations between pulmonary diseases (asthma, chronic obstructive pulmonary disease [COPD], and tuberculosis [TB]) and subsequent lung cancer risk have been reported, but few studies have investigated the association with different histologic types of lung cancer. METHODS: Patients newly diagnosed with lung cancer from 2004 to 2008 were identified from the National Health Insurance Research Database in Taiwan. Histologic types of lung cancer were further confirmed using the Taiwan Cancer Registry Database. Cox proportional hazards regression was used to calculate the hazard ratio (HR) of asthma, COPD, and TB and to estimate the risk of specific types of lung cancer. RESULTS: During the study period, 32,759 cases of lung cancer were identified from 15,219,024 insurants aged 20 years and older. In men and women, the adjusted HR estimates of squamous cell carcinoma were respectively 1.37 (95 % confidence interval [CI], 1.21-1.54) and 2.10 (95 % CI, 1.36-3.23) for TB, 1.52 (95 % CI, 1.42-1.64) and 1.50 (95 % CI, 1.21-1.85) for asthma, and 1.66 (95 % CI, 1.56-1.76) and 1.44 (95 % CI, 1.19-1.74) for COPD. Similarly, the adjusted HR estimates of adenocarcinoma were respectively 1.33 (95 % CI, 1.19-1.50) and 1.86 (95 % CI, 1.57-2.19) for TB, 1.13 (95 % CI, 1.05-1.21) and 1.18 (95 % CI, 1.09-1.28) for asthma, and 1.50 (95 % CI, 1.42-1.59) and 1.33 (95 % CI, 1.25-1.42) for COPD. The HRs of small cell carcinoma were respectively 1.24 (95 % CI, 1.01-1.52) and 2.23 (95 % CI, 1.17-4.25) for TB, 1.51 (95 % CI, 1.35-1.69) and 1.63 (95 % CI, 1.16-2.27) for asthma, and 1.39 (95 % CI, 1.26-1.53) and 1.78 (95 % CI, 1.33-2.39) for COPD. CONCLUSIONS: Asthma, COPD, and TB were associated with an increased risk of all major subtypes of lung cancer. The risk was the highest among women with TB.