Association of Lung Cancer and Tuberculosis: A Cross Sectional Study from Northwest of Iran

Tuberculosis (TB) is a life-threatening disease, which still remains a major public health concern in Iran, as the country is an endemic region for TB. On the other hand, carcinoma of the lung is the most common and lethal cancer. As the lung cancer involves respiratory system, it has many common connections with TB, too, and it is likely that immunosuppressant drugs, like the ones used in cancer treatments, increase the risk of TB development. To assess the possible association of TB and lung cancer, the current study evaluates the incidence of TB among patients with lung cancer. In the present cross-sectional study, patients with diagnosis of lung cancer were selected from the referral centers between 2011 and 2016. The TB among the patients was diagnosed, using radiographic pulmonary infiltration, M. tuberculosis culturing, and sputum smear. The diagnostic tests were done twice to certitude the results. From 845 cases entering the study, 9 patients (1.1%) were diagnosed with TB and the smear test was positive in 5 patients. The cases aged between 40 and 67 years old, with the mean age of 53.92 ± 8.02. Women had a significantly more average age than men and adenocarcinoma was the most common type of lung cancer with a rate of 57.63%. According to results of current study, there was a relationship between lung cancer and TB, while the incidence of TB in patients with lung cancer was more than the normal average rate of TB incidence in the region.