Presence of Nontuberculous Mycobacteria in Respiratory Specimen Does Not Change the Outcome of Lung Cancer: A Retrospective Matched Cohort Study

Rationale: Patients with lung cancer may sometimes have nontuberculous mycobacteria (NTM) isolated from their respiratory specimens.We aimed to investigate whether the presence of NTM in respiratory tract changes the clinical features and outcome of patients with lung cancer.Methods: Between 29 June 2016 and 16 September 2020, patients with lung cancer diagnosed in a medical center in northern Taiwan was retrieved.Among them, those whose respiratory specimens were culture-positive for NTM were identified (NTM group).For each one in the NTM group, a lung cancer patient whose respiratory specimens were culture-negative for NTM and who matched in age, sex, histology type, stage, and initial treatment was selected (control group).Survival of the two groups were compared by using Kaplan-Meier method and cox proportional hazards regression analysis.Results: During the study period, a total of 1483 patients with lung cancer were identified.Among them, 740 (49.9%) underwent sputum mycobacterial culture.The median age was 68 (range, 60 -77).Of them, 66 (9.2% in 740) having at least one NTM isolate were enrolled (NTM group).The median age of the NTM group was 74 years (range, 66 -81).The most common NTM species was Mycobacterium avium complex (29%).Compared with the control group, NTM group had a higher Charlson comorbidity index (8 vs. 4, p<0.001), a higher prevalence of interstitial lung disease (9 vs. 0, p=0.028), but a lower prevalence of diabetes mellitus (15 vs. 35, p=0.009).There was no difference in 2-year survival between NTM and control groups.The hazards ratio of presence of NTM in sputum for death was 1.10 (95% CI: 0.61 -2.03) in patients with lung cancer.Conclusions: NTM is present in 9.2% of patients with lung cancer, and probably has no negative impact on survival.