Clinical characteristics and survival of patients concurrently diagnosed with lung cancer and active pulmonary tuberculosis

Background: The diagnosis of pulmonary tuberculosis (TB) in patients suspected of lung cancer is difficult because of the similarities in signs, symptoms, and radiologic results. The clinical and radiologic characteristics of the co-occurrence of pulmonary TB and lung cancer have not been fully evaluated. Methods: Patients diagnosed with lung cancer and active pulmonary TB from January 2009 to December 2017 in four hospitals of the Catholic University of Korea were retrospectively reviewed. The clinical characteristics, including the TB diagnosis methods, lung cancer pathology, staging, initial radiographic features, and survival were analyzed and compared to 575 lung cancer patients without active pulmonary TB from the same hospitals. Results: Forty-eight (0.48%) of the 9,936 lung cancer patients had active pulmonary TB confirmed for M. tuberculosis at the time of the initial cancer diagnosis. The majority of the patients (95.9%) had non-small cell lung cancer and the most frequent findings were a mass-like lesion (79.2%) and separate nodules (75%). When compared to lung cancer patients without TB, the body mass index (BMI) was lower (21.4 vs. 23.1, P=0.001) and clinical stages were advanced in the lung cancer patients with TB; T3-4 (70.9% vs. 50.6%, P=0.002), N2-3 (85.2% vs. 55.6%, P<0.001); M1 (65.9% vs. 44.5%, P=0.007). Interestingly, lung cancer with TB was associated with lower mortality [hazard ratio (HR) =0.35, 95% CI: 0.21–0.60]. Conclusions: Rarely diagnosed concurrent active TB in lung cancer patients was associated with lower BMI and advanced clinical stages. Active investigation of and treatment for active pulmonary TB in lung cancer patients might possibly improve patient outcomes.