Lung cancer is the most commonly diagnosed cancer annually since 1985. Worldwide, there are 1.61 million new cases of lung cancer per year, with 1.38 million deaths, making lung cancer the leading cause of cancer-related mortality.
In India, approximately 63,000 new lung cancer cases are reported each year. The major risk factor for developing lung cancer is tobacco use and this disease is often viewed solely as a smoker’s disease. However, a significant number of patients with lung cancer have no history of smoking.
Globally, lung cancer in never-smokers demonstrates a marked gender bias, occurring more frequently among women. In particular, a high proportion of Asian women diagnosed with lung cancer are never-smokers. Although smoking-related carcinogens act on both proximal and distal airways inducing all the major forms of lung cancer, cancers arising in never-smokers target the distal airways and favour adenocarcinoma histology.
Never-smokers with lung cancer present with more advanced disease, usually at an earlier age, again suggesting a biologically different disease from tobacco-related lung cancer,In non-smokers, various factors are thought to contribute to the risk of lung cancer, including environmental tobacco smoke (second-hand smoke), other environmental exposures including asbestos and arsenic, radon, viruses like human papilloma virus, benign lung diseases like idiopathic pulmonary fibrosis, estrogens and possibly genetic factors, especially in patients with a family history of early-onset cancer. in patients from rural India, there may be an additional contribution from indoor air pollutants, like the fumes from cooking oil and the smoke from a coal stove.
At the molecular level, mutations of EGFR, HER2, EML4-ALK and less frequently KRAS mutations (especially transition mutations) may play a role. Routine molecular testing is still not the standard of carelung cancer in non-smokers represents a distinct clinical entity with unique epidemiological, clinical and molecular characteristics. A high level of suspicion leading to prompt diagnosis, screening and treatment with targeted agents in suitable cases should be the prime goal.
Dr P Harsha Vardhana Varma Penumatsa
Qualification : MBBS,M.D
Specialty: Chest Physician