The study highlighted "biomass fuel use" amongst key contributors to lung cancer, "particularly among women."
Published Jan 17, 2026 | 8:00 AM ⚊ Updated Jan 17, 2026 | 8:00 AM
Representational image. Credit: iStock
Synopsis: Lung cancer among non-smoking women in southern India is rising alarmingly, with Thiruvananthapuram recording the fastest growth at 6.7% annually. A major study highlights adenocarcinoma as the dominant subtype, driven by air pollution, biomass fuel smoke, and second-hand tobacco exposure. Researchers warn of an “invisible epidemic,” urging stronger data, diagnostics, and prevention beyond tobacco control to address this public health crisis.
In Thiruvananthapuram, a troubling pattern is emerging. Lung cancer amongst women is rising at 6.7 percent annually—the fastest rate in India. Yet fewer than 1 percent of women in the district smoke tobacco.
Across southern India, a similar story is unfolding. In districts where female tobacco use remains below 10 percent, lung cancer incidence is climbing at rates that alarm researchers and challenge conventional understanding of the disease.
A major study published in the Indian Journal of Medical Research has documented what researchers describe as an “invisible epidemic”—a surge in lung cancer amongst women in Kerala, Tamil Nadu, and Karnataka who have never touched a cigarette, driven by environmental and lifestyle factors that public health campaigns have largely overlooked.
The study analysed data from 57 populations across India, revealing that southern women face some of the country’s most dramatic increases in lung cancer incidence.
“An increasing trend in incidence was observed in 7 out of 8 populations, with the highest AAPC in Thiruvananthapuram (6.7), followed by Dindigul (5.5) and Kollam (5.3),” the researchers reported, referring to the Average Annual Percent Change (AAPC)—a statistical measure of how quickly disease rates are climbing each year.
These figures represent growth rates far exceeding those seen amongst men in the same regions, and amongst both genders in most other parts of India.
In Thiruvananthapuram, where the annual growth rate reached 6.7 percent, tobacco use amongst women stands at just 0.8 percent. In Kollam, with a growth rate of 5.3 percent, only 1.6 percent of women use tobacco. Dindigul, with the second-highest growth rate at 5.5 percent, reports female tobacco prevalence of 6.5 percent.
“Globally and in India, lung cancer is rising among women, including younger age groups, despite tobacco use being <10 per cent, suggesting other contributing factors,” the study noted.
The disconnect between these soaring cancer rates and minimal smoking prevalence has forced researchers to look beyond cigarettes for explanations.
Adding to the mystery is the type of lung cancer increasingly diagnosed amongst southern women. Adenocarcinoma, a subtype more commonly associated with non-smokers, has become the dominant form of the disease.
In Bengaluru, the transformation has been particularly dramatic. “Among women, adenocarcinoma increased as well, most notably in Bengaluru (23.9 percent to 55.7 percent),” the study reported, documenting the shift from 1993-1997 to 2013-2017.
Today, more than half of all lung cancer cases amongst women in Bengaluru are adenocarcinoma—a proportion that continues to rise.
Across the south, the pattern repeats. In Ahmedabad, adenocarcinoma accounts for 59 percent of female lung cancer cases. The study found that “adenocarcinoma was the most common subtype in 20 populations” amongst women.
“Adenocarcinoma was the most common and fastest-growing lung cancer subtype, especially among women, consistent with global trends,” the authors emphasised.
This matters because adenocarcinoma develops through different pathways than the squamous-cell carcinoma traditionally linked to heavy smoking. Its rise amongst non-smoking women points to environmental and lifestyle exposures that deserve urgent attention.
With smoking largely ruled out as the primary driver, researchers have identified several factors that may explain the surge in female lung cancer rates.
Air pollution tops the list. “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,” the researchers reported.
Women in both urban and rural southern India face significant exposure to harmful particulates. In cities like Bengaluru and Hyderabad, outdoor air pollution from traffic and industry creates a persistent health hazard. Rural women, meanwhile, face different but equally serious risks.
Biomass fuel use emerged as a particularly significant threat. Millions of southern Indian women spend hours each day cooking over wood, dung, or crop residue fires in poorly ventilated kitchens, inhaling smoke that contains many of the same carcinogens found in cigarettes.
The study highlighted “biomass fuel use” amongst key contributors to lung cancer, “particularly among women.”
Second-hand smoke adds another layer of risk. Even women who never smoke themselves face exposure through family members and public spaces. The study noted that such exposure “is reported in 48.5 percent of adults,” meaning nearly half of India’s population—including millions of southern women—regularly inhale tobacco smoke against their will.
These factors combine to create what researchers describe as a “perfect storm” of risk for southern women: minimal awareness, substantial exposure, and limited prevention efforts targeting non-smoking populations.
The study documented current incidence rates that already rank amongst India’s highest for women. “Among women, the highest ASIR was in Hyderabad (6.8), followed by Bangalore (6.2),” with the age-standardised incidence rate measured per 100,000 population.
But the projections for 2030 suggest the crisis will intensify. Using statistical models to forecast future trends, researchers predicted that Bengaluru will reach an incidence rate of 8.1/100,000 women by the end of the decade.
“Among women, the corresponding forecasted ASIRs for 2030 are; Bengaluru: 8.1 , Barshi: 1.9 , Chennai: 6.2, Delhi: 6.9 , Dindigul: 2.8 , Kollam: 7.6, Mumbai: 6.1 and Thiruvananthapuram: 7.6 ,” the study detailed.
Kollam and Thiruvananthapuram are both projected to reach rates of 7.6/100,000, placing them amongst the highest in the country.
These projections assume current trends continue—meaning that without intervention, thousands of additional southern women will develop lung cancer over the coming years, most of them non-smokers who never considered themselves at risk.
Concerningly, the rise in lung cancer is not confined to elderly women. The study found increasing incidence “among women, including younger age groups,” suggesting that environmental exposures are affecting women across the lifespan.
“Similarly increasing-trend were observed in both <60 and ≥60 yr,” the researchers noted, indicating that both younger and older women face rising risk.
This pattern suggests that whatever environmental or lifestyle factors are driving the epidemic have been present and intensifying over several decades, affecting multiple generations of southern women.
The invisible nature of this epidemic has created a significant gap in prevention efforts. Anti-tobacco campaigns, which form the backbone of most lung cancer prevention programmes, fail to reach the women most at risk.
“Around 25 percent of lung cancer cases worldwide are linked to non-tobacco factors,” the study noted, highlighting how traditional approaches miss a substantial portion of the disease burden.
For southern Indian women, that proportion appears to be far higher. With tobacco use below 10 percent in many areas but lung cancer rising rapidly, the majority of cases must stem from non-smoking risk factors.
Yet public awareness campaigns rarely mention biomass fuel smoke, air pollution, or second-hand smoke as lung cancer risks. Women cooking over traditional stoves or living in polluted cities may have no idea they face elevated risk.
The study also uncovered potential weaknesses in mortality surveillance that may obscure the true scale of the crisis.
“Low MIR suggests underreported mortality, highlighting the need for improved death reporting,” the researchers noted, referring to the mortality-to-incidence ratio—a measure of what proportion of cancer cases result in death. Mortality-to-incidence ratio (MIR), which compares the number of deaths to new cases and indicates how deadly the disease is in a given population.
Globally, lung cancer has a very high mortality rate, with most patients dying within a year of diagnosis. Yet many southern registries reported much lower mortality-to-incidence ratios, suggesting that deaths are not being properly attributed to lung cancer.
This means the invisible epidemic may be even larger than current data suggests, with an unknown number of women dying from lung cancer that is never properly diagnosed or recorded.
The study’s authors emphasised that addressing this crisis requires moving beyond conventional tobacco control strategies.
“Regional disparities in lung cancer burden were observed, with a higher proportion of adenocarcinoma, particularly among women. An upward trend in incidence is projected in the coming decades,” they concluded.
“Strengthening data systems, diagnostics, and targeted prevention is crucial. Further research is needed to identify region-specific lung cancer drivers beyond tobacco, including environmental, occupational, and lifestyle factors, key to effective prevention and early detection,” the researchers urged.
For the women of southern India, the message is stark: lung cancer is no longer a disease that only affects smokers. Environmental exposures that seem ordinary—cooking fuel, traffic pollution, second-hand smoke—are combining to create a public health crisis that demands urgent attention.
The analysis was conducted by researchers from the Regional Cancer Centre in Thiruvananthapuram and the Manipal Academy of Higher Education, examining data from populations across India.
(Edited by Amit Vasudev)
