Last Updated:
Lung cancer is commonly ascribed to smoking and tobacco consumption
Passive smoking is also equally dangerous in which the non-smoker is exposed to tobacco smoke released in the immediate atmosphere from smokers in the family or friend circle. (Photo: Shutterstock)
On one sunny afternoon, 54 year old Radha (name changed), a devoted housewife in a Jain household, felt an unuaual scratch in her throat. A moment later, she coughed, her breath catching as she saw bright red blood staining her hands. She had always lived a disciplined life – strictly vegetarian, deeply rooted in her faith, practicing and even teaching yoga for years. Her days were filled with warmth, managing their thriving cloth shop alongside her husband, surrounded by family and contentment. But over the next few days, as the coughing worsened and exhaustion set in, her world began to shift. A series of medical tests confirmed the unthinkable – metastatic lung cancer. In an instant, everything she had known and built seemed to collapse, leaving behind a stark, uncertain future.
Dr. Karan Chanchlani, Consultant – Radiation Oncology, Manipal Hospital, Baner, Pune takes us through non-smokers and lung cancers
Lung cancer is commonly ascribed to smoking and tobacco consumption. However, there are many other causes of lung cancer besides smoking. These days we are seeing a lot of patients, especially females but also males, who have never been exposed to tobacco/smoking and still develop lung cancer. Passive smoking is also equally dangerous in which the non-smoker is exposed to tobacco smoke released in the immediate atmosphere from smokers in the family or friend circle. Smoking through vapes or e-cigarettes also contains harmful vapours that prove carcinogenic. A more inconspicuous exposure that frequently goes unnoticed in India is use of meshri, which is nothing but dried, roated tobacco leaves used as a dant-manjan. Many Indian ladies who otherwise don’t smoke (active as well as passive smoking) are exposed to the fumes of tobacco that are harmful.
Air Pollution due to vehicular smoke, transportation, industries, power generation, dust and agriculture is now becoming the most common cause of lung cancers in certain pockets of the world. Exposure to fuel smoke has been associated with various diseases, including chronic obstructive pulmonary disease, acute respiratory infections, and various types of cancer, particularly lung cancer. Incomplete combustion of gases leads to the emission of gases, including sulfur dioxide, carbon monoxide, carbon dioxide and nitrogen oxide, as well as Polycyclic aromatic hydrocarbons (PAHs), formaldehyde and heavy metals. These are usually released as microscopic solids or liquid droplets, called Particulate Matter, that are so small that they can be inhaled and cause serious health problems. Pollution and Particulate Matter are as Group 1 carcinogens (definitive human carcinogens) by the IARC. The Global Burden of Disease Study (2019) estimated that nearly 250,000 lung cancer deaths annually worldwide are caused by air pollution. Various studies have estimated an increase in the risk of lung cancers ranging from 15-36% for every 10 mcg/m3 increase in particulate matter (PM2.5 and PM10). Indoor pollution from long-term exposure to biomass smoke (chulha) is often overlooked and under-studied risk factor in Indian context.
Diet and Alcohol – High intake of meat, in particular fried or smoked red meat, may increase the risk of lung cancer and this may be related to formation of nitrosamines during cooking. Conversely, there is evidence from case–control studies that a diet rich in vegetables and fruits, especially cruciferous vegetables, may exert some protective effect against lung cancer. Heavy coffee and alcohol consumption related to higher incidences of lung cancers, although they are frequently associated with tobacco consumption. Therefore, it is difficult to elucidate the contribution of alcohol/coffee to lung carcinogenesis while properly controlling for the potential confounding effect of tobacco.
Occupational Exposures – Miners, stone cutters, foundry workers, smelters, electrolysis workers and heavy alloy manufacturers have increased exposure to variety of carcinogens like asbestos, silica, radon, nickel, chromium and PAHs. It is important to follow precautions like wearing masks, barriers and follow safe industrial practices in these occupations.
Genome-wide association studies (GWAS) have identified various genes that increase the risk of developing lung cancers. However, it is unclear that in absence of other risk factors, what is the contribution of these genetics alone in the development of cancer. In addition, it is unclear as to how many of lung cancers are hereditary. Patient with previously existing chronic lung diseases like asthma, COPD, pulmonary tuberculosis and its sequelae may be at an increased risk although it is not conclusively established.
