Lung cancer remains a significant health threat, claiming countless lives worldwide. While smoking has historically been the primary culprit, new research from The Lancet Regional Health Southeast Asia Journal reveals a complex and alarming reality – lung cancer is increasingly affecting non-smokers in the region. A team of doctors, predominantly from Tata Memorial Centre in Mumbai, conducted the study titled ‘Uniqueness of lung cancer in Southeast Asia’, shedding light on the distinct characteristics of the disease in Southeast Asia, particularly India. Their findings highlight a “substantial proportion of patients” with lung cancers being non-smokers, signifying a shift in the understanding of its causes.
The research emphasizes that the genetic makeup of lung cancer in India is unique, influenced by the country’s diverse population. India holds the unfortunate distinction of being Asia’s second-largest contributor to lung disease, reporting a staggering 72,510 lung cancer cases and 66,279 deaths in 2020 alone.
Delving deeper into the reasons behind the rising lung cancer cases among non-smokers, the study pinpoints air pollution as a major contributing factor. India, grappling with a severe air pollution crisis, has seen New Delhi consistently ranked as the world’s most polluted capital city for four consecutive years starting in 2018. Prolonged exposure to particulate matter (PM) 2.5, asbestos, chromium, cadmium, arsenic, coal, and even second-hand smoke at home significantly elevates the risk of lung cancer. The World Air Quality Report 2023 by Swiss organization IQAir reveals that a staggering 1.33 billion people, representing 96 per cent of India’s population, are exposed to PM2.5 levels exceeding seven times the WHO’s recommended limit of 5 micrograms per cubic meter. This severe air pollution has fueled a surge in lung cancer incidence rates, rising from 6.62 per 100,000 in 1990 to 7.7 per 100,000 in 2019. Experts anticipate a significant escalation of these rates in urban areas by 2025.
Climate change further complicates the situation. Researchers, including those from the All India Institute of Medical Sciences (AIIMS), New Delhi, have reported in another paper from the same series that South Asian nations, including China, India, Indonesia, the Philippines, and Thailand, have been disproportionately impacted by natural disasters. These countries registered the highest number of lung cancer cases in 2020, exceeding 965,000 new cases. The authors emphasize, “As climate change continues to unfold, it magnifies the burden of lung cancer which is already a significant public health challenge in Asia.”
Beyond environmental factors, genetics play a crucial role. The study identifies factors like hormonal status, pre-existing lung disease, and genetic susceptibility as potential contributors to the increasing lung cancer incidence among never-smokers. A study published on PubMed highlights the prevalence of mutations in genes such as EGFR (epidermal growth factor receptor) in non-smokers diagnosed with lung cancer. These genetic anomalies can lead to uncontrolled cell growth and tumor development, independent of external factors like smoking, as confirmed by a study conducted by the National Cancer Institute.
Age also emerges as a significant factor. The study reveals that lung cancer tends to affect non-smokers in India up to a decade earlier than in many Western countries, with the average age of diagnosis ranging from 54 to 70. One contributing factor is India’s relatively younger population. The study notes, “The earlier age of presentation in India is likely to be a combination of the overall population pyramid structure in India (younger population, with a median age of 28.2 years; compared to the USA in which the median age is 38 years, and China, with a median age of 39 years).”
Dr. Kumar Prabhash, a contributing author from Tata Medical Centre’s medical oncology department, shared with The Times of India that despite the lower proportion of cancer cases in India compared to the West, the sheer size of India’s population makes the absolute number of cases substantial. He stated, “The incidence rate of lung cancer in the US is 30 per 1,000, but it’s 6 per 1,000 in India. Given our huge population, however, even the 6 per cent works out to a huge number of patients.” The research also points out that the male-to-female ratio of lung cancer cases reflects the higher tobacco use among men (42.4 per cent vs. 14.2 per cent among women), highlighting the stark gender disparity in tobacco consumption.
Further compounding the challenge is India’s high tuberculosis (TB) rate. Dr. Kumar Prabhash explained to The Times of India that TB presents a unique hurdle in India’s lung cancer landscape. He stated, “Diagnosis often gets delayed because of TB as both conditions mimic each other.” The study’s authors underscore the difficulty in accessing cutting-edge treatment modalities and molecules, stating, “Most treatments are developed abroad, and importing them adds to the cost.” They emphasize that the primary challenge lies in early identification and initiation of treatment. The study reinforces Prabash’s argument, stating, “Inequities in socioeconomic status and access to healthcare contribute to the differences in the lung cancer burden and mortality in low- and middle-income countries.”
Dr. Prabhash also pointed out, “Barely 5 per cent of lung cancer patients seek help in time for surgical help. We need to increase this number to at least 20 per cent like in the West.” This stark reality underscores the urgent need for raising awareness, improving access to healthcare, and promoting early detection to combat this multifaceted health crisis in Southeast Asia.
