Early and accurate diagnosis of TB and lung cancer vital: No excuse for misdiagnosis!

Bobby Ramakant *

Early and accurate diagnosis is a public health imperative for both diseases of epidemic proportions in Asia Pacific: tuberculosis (TB) and lung cancer. But since TB of the lungs (pulmonary TB) imitates lung cancer in many aspects including risk factors, symptoms, signs and radiographic findings, often misdiagnosis has a serious public health consequence! "Symptoms of cough, haemoptysis, chest pains, weakness, weight loss, fever and night sweats are common in both active pulmonary TB and symptomatic lung cancer.

In the meantime, radiographic findings of TB can mimic lung cancer such as mass-like lesion, pulmonary nodule, mediastinal lymph node enlargement or pleural effusion" said Dr Natthaya Triphuridet, Pulmonologist and Assistant Director for Medical Affairs at Chulabhorn Hospital, Bangkok, Thailand.

Dr Natthaya is also one of the faculty members for IASLC Asia Pacific Lung Cancer Conference (APLCC 2016) which will be held in Chiang Mai, Thailand during 13-15 May 2016.

Dr Sumitra Thongprasert, Conference Chair of APLCC 2016 and Special Content Editor of Journal of Thoracic Oncology, lamented that in the whole of South East Asia lung cancer is a major public health problem due to its high incidence and death rate - 90% of patients with lung cancer will die soon. In Thailand, lung cancer rates rank number one in men, and in women it is next to breast cancer. Dr Sumitra is also an Emeritus Professor at Maharaj Nakorn Hospital and Medical College, Chiang Mai University and senior Medical Oncologist at Bangkok Hospital, Chiang Mai.

TB in lung cancer patients?

But is there any association between TB and lung cancer? "An increased prevalence of active TB was reported in lung cancer patients (8–10 times higher compared with general population). Preexisting TB is an independent risk factor for lung cancer (no direct association). As an immuno-suppressive disease, lung cancer may promote TB infection or reactivation of latent TB infection, or cause new exogenous infection" explained Dr Natthaya Triphuridet.

"One-third of the world's population is infected with latent TB. The WHO South-East Asia region accounts for 41% of the global TB incidence. In 2014, TB prevalence in this region was 5.4 million cases while TB incidence was around 4 million. Thailand is one of the 22 high-burden TB countries. The burden of lung cancer is no less alarming. Lung cancer is the most common cancer in the world as well as the most common cause of death from cancer worldwide. The survival rate of lung cancer is strongly related to the stage of the disease. With delayed or late detection of lung cancer, there is a significant decrease in survival rate" said Dr Natthaya Triphuridet.

SDG 2030 target to end TB, reduce lung cancer by 1/3rd

UN member-countries have committed to Sustainable Development Goals (SDGs), which includes the target to end TB and reduce the burden of non-communicable diseases (including lung cancer) by one-third by 2030. But this SDG target will not be met if we continue to delay or misdiagnose either of the two: TB or lung cancer. Early and accurate diagnosis of both, TB and lung cancer, is as critical as providing standard treatment and care. WHO and national TB programmes have laid out diagnostic algorithms for TB which are backed by scientific evidence.

"As TB can mimic lung cancer, we are confronted with challenges in management of lung cancer in TB endemic areas in terms of screening, diagnosis, staging, treatment monitoring and surveillance. A study (done by Engels et al) reported that lung cancer mortality was substantially higher in lung cancer patients with TB than among those without TB" added Dr Natthaya.

Targeted TB testing and treatment of latent TB infection can make a big difference in not only early and accurate diagnosis of TB but also preventing latent TB infection from progressing to active TB disease. Screening for latent TB and active TB disease among lung cancer patients will also be useful, advises Dr Natthaya.

Dr Natthaya Triphuridet had received the prestigious International Association for the Study of Lung Cancer (IASLC) Global Mentorship Award 2013 for "Screening of Lung Cancer by Low-Dose CT (LDCT), Digital Tomosynthesis (DT) and Chest Radiography (CR) in a High Risk Population" in Australia. She sheds more light on how to accurately diagnose lung cancer.

Low-dose CT for lung cancer screening

"Now low-dose computerized tomography (LDCT) is the current standard technique for lung cancer screening. Based on a study, screening with LDCT resulted in a 20% lower lung cancer-specific mortality and 6.7% lower all-cause mortality than chest radiographs in the high risk group. In 2013, United States Preventive Services Task Force (USPSTF) has also recommended "annual screening for lung cancer with LDCT in adults aged 55-80 years who have a 30 pack-year tobacco smoking history and currently smoke or have quitted within the past 15 years" said Dr Natthaya, who is also the Principal Investigator of Integrative Lung Cancer Screening Project in Thailand. Despite evident public health advantages of using LDCT for lung cancer screening some challenges remain.

Tobacco smoking fuels both: TB and lung cancer

TB and lung cancer have another common risk factor: tobacco smoking. Almost all countries in Asia Pacific region have ratified the WHO Framework Convention on Tobacco Control (FCTC). Effective implementation of tobacco control in the region will have multiple public health benefits.

At IASLC Asia Pacific Lung Cancer Conference (APLCC 2016: www.aplcc2016.com) there will be focused sessions on lung cancer and tobacco control as well. APLCC 2016 will be a great opportunity for scientific updates on lung cancer related issues as well as academic discourses on how to effectively save lives from lung cancer in the region.