Pulmonary tuberculosis: A hurdle to overcome for early lung cancer diagnosis in TB burden countries

Abstract

Background: Bangladesh is ranked 6th among the Tuberculosis high burden countries. Sometimes, pulmonary tuberculosis (PTB) mimics the early symptoms of lung cancer. Developing countries like Bangladesh, with limited diagnostic facilities, often misdiagnose early lung cancer as smear negative PTB. According to national guidelines for PTB, smear negative PTB is defined as the cases diagnosed on the basis of X-ray abnormalities or suggestive histology and extra pulmonary cases without laboratory confirmation. This observational study has been done to find out the ratio of misdiagnosis of lung cancer as Smear Negative PTB. Methods: This observational study was done between June, 2017 to January, 2018 at OPD of NIDCH (National Institute of Diseases the Chest & Hospital), Dhaka, Bangladesh. Inclusion criteria for the confirmation of PTB were: symptoms not improving after 3 weeks of anti-TB treatment; non-improving chest X-ray; new symptoms; no prior anti-TB treatment; smear negative PTB. For confirmation of AFB (Acid fast bacillus) smear test, CT scan of chest, GeneXpert of sputum, Mycobacterium culture and histological confirmation were performed. During this period, 172 cases were included in the study. After confirmation of the diagnosis, every case was treated according to national TB guidelines and refered to other tertiary specialized hospitals. After changing of the treatment protocol, 3-weekly follow up was done for 2 months with chest X-ray and other blood parameters. Results: The investigations mentioned above were performed in all cases included in the study: 35 cases (20.34%) were diagnosed as lung cancer by histological confirmation. 81 cases were (47.09%) diagnosed as multidrug-resistant TB and 2 cases (1.16%) were diagnosed as extensively drug-resistant TB. Other cases (31.39%) were confirmed as PTB. Conclusions: In countries with a high tuberculosis burden and lack of facilities for guided biopsy or fine needle aspiration, except in tertiary hospitals, plays an important role in delay of early diagnosis of lung cancer. In addition, flexible national guidelines and DOT (direct observed therapy) of anti-TB drugs are given at no cost to patients are also contributory factors. In this short observational study, it was found that a number of patients received anti-TB drug based on clinical diagnosis has been diagnosed as Lung cancer that were previously diagnosed as Smear negative PTB on clinical ground and Chest X-ray. This finding suggests that national policy makers should consider that patients with smear negative PTB (clinical diagnosed PTB) need close follow up and proper referral to specialized & tertiary hospitals where there are facilities for confirming the diagnosis. To make and change in national guideline this observational study should be run in multi center in the country.