Association Between Pulmonary Mycobacterium Avium Complex Infection and Lung Cancer

Introduction: Patients with lung cancer are sometimes found to have respiratory cultures growing Mycobacterium avium complex (MAC). This study describes the clinical, pathologic, and radiographic ­characteristics of individuals who harbor concomitant lung cancer and MAC. Methods: Retrospective analysis of patients with positive respiratory cultures for MAC (370 men, 475 women) and with newly diagnosed lung cancer (792 men, 840 women) from 1995 to 2010. Results: Of the patients with respiratory cultures growing MAC, 8.6% of men and 6.3% of women had lung cancer. Twenty-five percent of patients with lung cancer and 3% with nonbronchiectatic benign lung disease grew MAC from their respiratory cultures. Significantly fewer women with both MAC and lung cancer were smokers than the control group of women with lung cancer and negative MAC cultures (68% versus 89%, p p = 0.01) Conclusions: The percentage of smokers among women with both MAC and lung cancer was lower than among the lung cancer control group who did not grow MAC. The presence of MAC in respiratory cultures of lung cancer patients was particularly associated with squamous cell carcinomas located in the periphery of the lung. Because MAC typically affects distal airways, this possible association between MAC infection and lung cancer warrants further study.