Latent TB infection in newly diagnosed lung cancer patients - A multicenter prospective observational study

Objectives: Lung cancer and tuberculosis (TB) share common risk factors and are associated with high morbidity and mortality. Coexistence of lung cancer and TB were reported in previous studies, with uncertain pathogenesis. The association between lung cancer and latent TB infection (LTBI) remains to be explored. Methods: Newly diagnosed, treatment-naïve lung cancer patients were prospectively enrolled from four referral medical centers in Taiwan. The presence of LTBI was determined by QuantiFERON-TB Gold In-Tube (QFT-GIT). Demographic characteristics and cancer-related factors associated with LTBI were investigated. The survival status was also analyzed according to the status of LTBI. Results: A total of 340 lung cancer patients were enrolled, including 96 (28.2%) LTBI, 214 (62.9%) non-LTBI, and 30 (8.8%) QFT-GIT results-indeterminate cases. Non-adenocarcinoma cases had higher proportion of LTBI than those of adenocarcinoma, especially in patients with younger age. In multivariate analysis, COPD (OR 2.41, 95% CI 1.25-4.64), fibrocalcified lesions on chest radiogram (OR 2.73, 95% CI 1.45-5.11), and main tumor located in typical TB areas (OR 2.02, 95% CI 1.15-3.55) were independent clinical predictors for LTBI. Kaplan-Meier survival analysis demonstrated patients with indeterminate QFT-GIT results had significantly higher 1-year all-cause mortality than those with LTBI (p<0.001) and non-LTBI (p = 0.003). In multivariate analysis, independent predictors for 1-year all-cause mortality included BMI. <18.5 (HR 2.09, 95% CI 1.06-4.14, p = 0.033), advanced stage of lung cancer (RR 7.76, 95% CI 1.90-31.78, p = 0.004), and indeterminate QFT-GIT results (RR 2.40, 95% CI 1.27-4.54, p = 0.007). Conclusions: More than one-quarter of newly diagnosed lung cancer patients in Taiwan have LTBI. The independent predictors for LTBI include COPD, fibrocalcified lesions on chest radiogram, and main tumor located in typical TB areas. The survival rate is comparable between LTBI and non-LTBI cases. However, indeterminate QFT-GIT result was an independent predictor for all-cause mortality in lung cancer patients.