India’s lung cancer burden is rising unevenly across regions, with new evidence showing that smoking alone does not explain who gets the disease and who dies from it, finds an alarming study published
in the Indian Journal of Medical Research.
According to an analytical study – “region-wise lung cancer burden, long-term trend & time-series forecasts in India…” described as “the first and most up-to-date analysis of burden of lung cancer and tobacco and alcohol use across 57 populations in six Indian regions,” found clear regional disparities.
Lung cancer incidence was higher among men in the south, north and north-east, and among women in the north-east. While high tobacco use explains much of the burden in the north-east, the picture is different elsewhere.
The researchers noted that the “southern region reported lower substance use (<25 per cent) but still reported high lung cancer ASIR rates, indicating other contributing factors.” This mismatch between smoking levels and cancer incidence strengthens concerns that environmental exposures, including polluted air, may be playing a significant role.
The authors of the study have urged for “research beyond tobacco usage” to understand the reasons behind the growing incidence. “The burden of lung cancer in India shows regional disparities, with more adenocarcinoma, especially among women,” wrote the authors of the study in the conclusion. “Incidence is projected to rise, while a low mortality-to-incidence ratio suggests underreported mortality, underscoring the need for better death reporting. Region-specific research beyond tobacco use is essential.”
The study published in IJMR – a peer-reviewed open-access medical journal published by the Indian Council of Medical Research (ICMR) – is being conducted by researchers at the Division of Cancer Epidemiology and Biostatistics, Regional Cancer Centre, Thiruvananthapuram and Manipal Academy of Higher Education, Karnataka, India.
Air pollution emerges as a critical risk
The study underlined that smoking is not the only cause of lung cancer. It stated that “around 25 per cent of lung cancer cases worldwide are linked to non-tobacco factors,” and cited research identifying “particulate matter in air pollution as a major cause of lung cancer.”
“A study identified particulate matter in air pollution as a major cause of lung cancer. In India, an estimated 1.7 million deaths are attributable to air pollution. Biomass fuel use and second-hand smoke exposure (reported in 48.5 per cent of adults) are also key contributors to lung cancer, particularly among women,” the authors wrote while quoting other studies.
The authors also pointed to other non-smoking risks that often overlap with polluted environments, including biomass fuel use and widespread exposure to second-hand smoke, which has been “reported in 48.5 per cent of adults.” These factors disproportionately affect women, offering one explanation for why lung cancer is rising among women despite tobacco use being below 10 per cent in most regions.
Rising cases, especially among women
The study found that “Adenocarcinoma was the most common and fastest-growing lung cancer subtype, especially among women, consistent with global trends.” Adenocarcinoma is a cancer that starts in the gland cells lining of human organs.
The analysis also found “an increasing trend in the incidence of lung cancer” among men, but the rise was steeper among women. According to the study, “women showed a higher (average annual percentage change) AAPC than men,” and lung cancer is increasing despite tobacco use being less than 10 per cent, suggesting other contributing factors.” The fastest-growing subtype was adenocarcinoma, particularly among women — a pattern that aligns with global research linking this subtype more strongly to air pollution than to smoking.
Lung cancer incidence was also higher and increasing among older adults of both genders, reflecting the combined effects of ageing and long-term exposure to harmful environmental and lifestyle factors.
Picture at the regional level
At the regional level, the picture remained complex. Also, the analysis found “an increasing trend in the incidence of lung cancer… among men,” with Kollam showing the highest rates over time, alongside tobacco use of 56.8 per cent. Even where tobacco consumption has fallen, the disease burden may reflect past exposure, as lung cancer often develops after a long latency of 10–30 years.
Areas such as Srinagar, Pulwama, Kannur and Kasargod reported high lung cancer incidence despite low alcohol use and, in some cases, modest tobacco prevalence. Conversely, districts like Wardha, Muzaffarpur and Prayagraj showed very high tobacco use but low reported lung cancer rates, raising concerns about underreporting, access to care, or patients seeking treatment elsewhere. In Mumbai, a sharp decline in male lung cancer incidence, also noted in earlier studies, may reflect data collection issues rather than a true fall in cases.
Data gaps hide the full impact
Despite the growing burden, lung cancer outcomes remain poor. “45 per cent of lung cancer cases in India are diagnosed at a distant stage, contributing to high mortality,” the study noted. While mortality-to-incidence ratios varied across regions, the authors cautioned that “low mortality to incidence ratio (MIR) may reflect underreporting of lung cancer deaths,” raising concerns that the true toll is being underestimated.
The study acknowledged limitations, including the absence of population-specific data on air pollution and occupational exposure, which prevented direct measurement of their impact. Still, the repeated observation of high lung cancer rates in areas with low tobacco and alcohol use points towards environmental causes that demand closer attention.
In conclusion, the authors observed “regional disparities in lung cancer burden,” with incidence projected to rise further in the coming decades. They stressed the need for better death reporting, stronger cancer registries and “further research… to identify region-specific lung cancer drivers beyond tobacco, including environmental, occupational, and lifestyle factors.” As India continues to battle worsening air quality, the findings add urgency to tackling pollution not just as an environmental issue, but as a growing cancer risk.
