Association of pulmonary nontuberculous mycobacteria with the outcomes of patients with lung cancer: A retrospective matched cohort study with a special emphasis on the impact of chemotherapy

Abstract

Abstract Introduction: Nontuberculous mycobacteria (NTM) may be present in the respiratory tract of patients with lung cancer. We investigated the association of pulmonary NTM with the clinical features and outcomes of patients with lung cancer. Methods: Between 2015 and 2019, the data of patients diagnosed with lung cancer at a medical center in northern Taiwan were analyzed. Patients whose respiratory specimens were culture-positive for NTM were identified (NTM group). For each patient in the NTM group, a matched control was selected (control group). The survival of the two groups was compared using the KaplaneMeier method and Cox proportional hazards regression analysis. Results: Among 8718 patients with lung cancer, 5418 (62.1%) underwent a sputum mycobacterial culture. At least one NTM species was isolated from 138 (2.5%) patients. The median age was 72 years (range: 64e80). In the NTM group, 19.8% fulfilled both the microbiological and radiographic criteria for the diagnosis of NTM lung disease. Compared with the control group, the NTM group exhibited a lower body mass index (22.4 vs. 23.6, p Z 0.025) and a higher prevalence of structural lung disease (38.9% vs. 22.2%, p Z 0.004). The two-year survival was not significantly different between the two groups (hazard ratio [HR]: 1.110; 95% confidence interval [CI]: 0.702e1.754, p Z 0.656). In patients receiving chemotherapy, pulmonary NTM was associated with worse survival (HR: 2.497, 95% CI: 1.262e4.943, p Z 0.009). Conclusions: Except in patients receiving chemotherapy, pulmonary NTM may not be clinically relevant in patients with lung cancer.