Medical Science: Updates and Prospects Vol. 9

Lung cancer is the second most commonly diagnosed cancer globally, with tobacco smoking as the commonest factor responsible for most cases. In India, it is the commonest cancer among men and ranks fourth in women. It has a significant disease burden in the north-eastern part of India.  The incidence of lung cancer in Manipur, a northeastern state of India, is disproportionately high despite the smoking prevalence. This suggests that there could be other major contributing factors, such as environment and genetic predisposition.

This review focuses on indoor radon exposure, a naturally occurring radioactive gas linked to lung cancer. Radon, along with other carcinogens like air pollution, asbestos and arsenic, poses a significant risk for lung cancer. While tobacco smoking is the leading cause of lung cancer, indoor radon exposure is particularly concerned in non-smokers, as it is the second leading cause of lung cancer worldwide.  The geological substrate on which buildings are settled, the soil composition, construction materials, ventilation and seasonal changes affect indoor radon build-up, concentrations or levels. Research has shown that prolonged exposure to indoor radon can lead to DNA damage, mutations and increase the risk for lung cancer. Studies on lung cancer in underground and uranium miners and, more recently, home-based indoor radon research have confirmed a clear link between indoor radon exposure and lung cancer risk, with no safe exposure threshold.

Manipur has high radiation levels. A study on soil radioactivity in the region had found higher-than-average Global and National levels of radium, thorium and potassium content. Building materials like sand, bricks and RCC houses in the region could have contributed to elevated indoor radon concentrations that could possibly increase lung cancer cases. This review emphasizes the need for further studies to assess the indoor radon concentrations in homes and local buildings. It advocates for public health initiatives, stricter regulations on building materials, improved ventilation in homes and workplaces to reduce indoor radon exposure and lower the lung cancer incidence. Enhanced awareness and preventive measures are crucial in addressing the growing lung cancer burden. In regions like Manipur with high radioactivity levels, awareness about indoor radon becomes very important, besides smoking. Smoking co-exposure with indoor radon is also to be emphasised for prevention and the decrease of lung cancer cases.