The rising incidence of lung cancer in India: An analytical study on causes, trends and public health implications

ISSN: 2583-9209; SJCSIT Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||1 The rising incidence of lung cancer in India: An analytical study on causes, trends and public health implications *1Vanita Patil, 2Sandhya Khade, 3Shribhiksha Jadhav, 4Sanika More *1Prof, Department of Computer Applications and Management, D.Y. Patil Institute of Computer Applications and Management, Akurdi, Pune 2,3,4Student, Department of Computer Applications, D.Y. Patil Institute of Computer Applications and Management, Akurdi, Pune Abstract: Lung cancer has emerged as one of the most important public health concerns in India over the last decade. Recent research published between 2018 and 2025 highlights significant changes in incidence, histological distribution, molecular patterns, and socioeconomic burden. Population-Based Cancer Registries (PBCRs) report rising or stable-but-high incidence in many regions, with Mizoram continuing to record the highest age-adjusted rates in Asia. Hospital-based cohorts reveal adenocarcinoma surpassing squamous cell carcinoma, while molecular studies document a high prevalence of Epidermal Growth Factor Receptor (EGFR) mutations and Anaplastic Lymphoma Kinase (ALK) rearrangements. Despite advances, over half of patients are still diagnosed at Stage IV, with median survival around 10–12 months. Risk attribution studies confirm tobacco, particularly bidi smoking, as the dominant cause, but biomass fuel exposure, long-term incense use, and worsening urban air pollution also contribute significantly. The financial burden of targeted therapies and immunotherapies remains catastrophic for families, forcing many to discontinue treatment prematurely. This study synthesizes Indian evidence published between 2018 and 2025 to present a comprehensive analysis of incidence, risk factors, histological and molecular trends, stage of diagnosis, survival outcomes, and socioeconomic implications. Our findings indicate that lung cancer in India is largely preventable, but addressing it requires strong tobacco control, clean household energy, urban air quality management, early detection, and financial protection for patients. Keywords: Lung cancer; India; Bidi smoking; Air pollution; Public registry; Public health. 1. Introduction: Lung cancer is now recognized as one of the leading causes of cancer-related mortality in India, and recent studies have shown that the disease burden is increasing in several regions. Between 2018 and Volume-3|| Issue-3||2025||Sept-Dec ISSN: 2583-9209; SJCSIT Vanita et al., Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||2 2025, new data from the Indian Council of Medical Research (ICMR) – National Cancer Registry Programme (NCRP) and hospital-based studies have deepened our understanding of this malignancy. According to PBCR updates published between 2019 and 2022, lung cancer ranks among the top five cancers in Indian men, with ageadjusted incidence rates (AARs) highest in Mizoram (38.8 per 100,000 men and 37.9 per 100,000 women) [1]. Urban centers such as Delhi, Bangalore, and Chennai show steady increases in incidence, reflecting both environmental exposures and improved detection. Histological patterns are also shifting. A 2020 update from the All India Institute of Medical Sciences (AIIMS) reported adenocarcinoma as the most common subtype (34%), surpassing squamous cell carcinoma (28.6%) [18]. Multicenter hospital studies conducted between 2021 and 2023 confirm this trend, showing adenocarcinoma at 35–40% of cases [21]. This aligns with global patterns and is believed to result from changes in tobacco consumption, rising exposure to biomass fuels and air pollution, and improved diagnostic techniques. Risk factor analysis from recent Indian case–control studies shows that bidi smoking carries an odds ratio (OR) of 4.2–8.3 for lung cancer, which is higher than for cigarette smoking (OR 2.0–5.0) [16]. Biomass fuel exposure increases risk by twoto threefold in women [15]. Air pollution, particularly PM2.5 exposure in metropolitan cities like Delhi, contributes to 8–12% of urban lung cancer cases [16]. Long-term incense use has also been identified as a smaller but significant contributor, with ORs around 1.5–2.0. Molecular data from 2018–2025 provide new insights into the Indian lung cancer profile. EGFR mutations are found in 23–30% of Indian patients [18, 19], while ALK rearrangements are detected in 10–12% [20]. ROS1 rearrangements occur in 2-3% of cases. These rates are closer to East Asian than Western cohorts, providing opportunities for targeted therapies but also exposing inequities due to financial inaccessibility. The clinical reality remains grim: over 55% of Indian lung cancer patients present with Stage IV disease [17], while only 20–25% are detected at potentially curable Stages I–II. Median survival for these advanced cases remains 10–12 months [22]. High treatment costs—₹60,000– 100,000 per month for targeted agents—cause catastrophic health expenditures, with many families forced to discontinue treatment prematurely. This paper consolidates Indian data published between 2018 and 2025. It aims to: (1) document incidence and epidemiological trends; (2) analyze risk factors; (3) examine histological and molecular patterns; (4) evaluate stage at presentation and survival; and (5) assess public health and financial implications. 2. Theoretical background: Lung cancer is a malignant neoplasm of the respiratory epithelium and one of the most aggressive ISSN: 2583-9209; SJCSIT Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||3 cancers encountered in clinical medicine. Its development is influenced by both environmental exposures and molecular alterations, which together drive carcinogenesis, histological subtype patterns, and clinical outcomes. In India, understanding these mechanisms is particularly important because of the interplay between unique risk factors such as bidi smoking, biomass fuel, and air pollution, alongside genetic susceptibility markers like EGFR and ALK. 2.1. Classification of lung cancer: Lung cancers are broadly classified into two categories: non-small cell lung cancer (NSCLC), which accounts for about 85–90% of cases, and small cell lung cancer (SCLC), which contributes 10–15%. NSCLC is further subdivided into adenocarcinoma (ADC), squamous cell carcinoma (SCC), and large cell carcinoma. Historically, SCC was the predominant subtype in Indian populations, particularly among male smokers. However, contemporary cohorts have documented a rise in adenocarcinoma, which now comprises 30–40% of cases in tertiary centers [21]. SCLC, though less common, is clinically significant for its aggressive behavior, early metastasis, and initial responsiveness to chemotherapy, followed by rapid relapse. In Indian studies, its prevalence has remained around 15– 16% [17]. 2.2. Carcinogenesis: environmental and genetic drivers: Carcinogenesis in lung cancer follows a multistep model, where repeated exposure to carcinogens initiates DNA damage and drives mutations in oncogenes and tumor suppressor genes. 1. Tobacco: Bidi smoke delivers higher concentrations of tar, nicotine, and carbon monoxide than cigarettes. Case–control studies report odds ratios of 4.2–8.3 for heavy bidi smokers, compared to 2.0–5.0 for cigarette smokers [16]. This makes bidis a particularly dangerous form of tobacco. 2. Biomass Fuel: Combustion of wood, dung cakes, and crop residues produces high levels of polyaromatic hydrocarbons and benzene, linked with lung cancer among nonsmoking rural women [15]. 3. Incense Burning: Long-term incense use (>30 years) was associated with an OR of 2.3 in an Indian case–control study. 4. Air Pollution: Studies in Delhi demonstrate a 1.2–1.5-fold increase in risk with rising PM2.5 exposure [16]. 5. Occupational Exposures: Workers in asbestos, construction, and pesticide industries show elevated risks (OR ~2.0–2.5). Together, these exposures explain India’s unique risk profile, distinct from Western populations where cigarette smoking alone predominates. Volume-3|| Issue-3||2025||Sept-Dec ISSN: 2583-9209; SJCSIT Vanita et al., Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||4 2.3. Clinical presentation and natural history: Indian patients often present late, typically at Stage III or IV disease. Symptoms such as chronic cough, hemoptysis, and weight loss are frequently mistaken for tuberculosis (TB) or chronic obstructive pulmonary disease (COPD), leading to delayed referrals. In the AIIMS cohort, 55% of patients presented at Stage IV [17]. Similarly, the Kolkata study found that more than 55% of cases were advanced at diagnosis. The natural history is poor: untreated NSCLC carries a median survival of less than 12 months, while SCLC often progresses within 6–9 months [22]. Even with treatment, survival outcomes remain significantly lower than in developed countries. 2.4. Molecular pathology: Advances in molecular biology have identified driver mutations in lung cancer. These include: 1. EGFR mutations: Found in 25–30% of Indian adenocarcinoma patients [18, 19]. 2. ALK rearrangements: Present in ~11% of Indian adenocarcinoma patients [20]. 3. KRAS and TP53 mutations: Less commonly studied in Indian cohorts but contribute globally to tumorigenesis. 4. ROS1 rearrangements: Occur in 2–3% of cases. The presence of EGFR and ALK mutations positions Indian patients closer to East Asian than Western populations. Clinically, these biomarkers have revolutionized treatment by enabling targeted therapies such as tyrosine kinase inhibitors (TKIs) and ALK inhibitors, which significantly prolong survival in mutation-positive patients. However, real-world application in India is limited. Many patients cannot afford molecular testing, and targeted therapies remain unaffordable for the majority. This inequity highlights the gap between theoretical advances and practical outcomes. 2.5. Public health framework: From a public health perspective, lung cancer is a disease with high preventability but poor prognosis once diagnosed. Models of population-attributable fraction (PAF) suggest that eliminating tobacco use could prevent up to 70% of lung cancers in India. Interventions targeting biomass fuels could further reduce risk in rural women. A simplified causal pathway can be constructed: 1. Exposures: Tobacco (especially bidis), biomass fuel, incense, air pollution, occupation. 2. Biological Impact: DNA damage -> EGFR/ALK mutations -> histological subtype changes. 3. Clinical Manifestation: Late-stage presentation, poor survival outcomes. ISSN: 2583-9209; SJCSIT Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||5 This framework underscores the importance of both primary prevention (tobacco control, clean fuels, pollution regulation) and secondary prevention (early detection, molecular testing). Figure. 1: Pathway of lung cancer in India 3. Literature review: 3.1. Incidence trends in India: Figure. 2: Incidence Trends in India Recent data from the Indian Council of Medical Research (ICMR) – National Cancer Registry Programme (NCRP) and PopulationBased Cancer Registries (PBCRs) show a heterogeneous but consistently high burden of lung cancer across the country. Mizoram continues to record the world’s highest incidence rates, with age-adjusted incidence rates (AARs) of 38.8 per 100,000 in men and 37.9 per 100,000 in women. This figure has remained stable since 2018 but continues to reflect the heavy tobacco use in the region. Other urban registries, including Delhi, Bangalore, and Chennai, have reported rising incidence trends [1]. Delhi’s PBCR showed an AAR of 13.2 in men and 6.2 in women in 2021, reflecting an increasing trend since the early 2000s. Chennai and Bangalore registries have Volume-3|| Issue-3||2025||Sept-Dec ISSN: 2583-9209; SJCSIT Vanita et al., Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||6 similarly shown moderate but steady increases in incidence, linked to both changes in diagnostic capacity and environmental exposures. Together, these findings suggest that while some highincidence areas remain stable, metropolitan cities are experiencing rising lung cancer rates, underscoring the disease’s evolving public health importance. Table. 1: PBCR Lung Cancer Incidence in India (2018–2023) Registry Men AAR (/100,000) Women AAR (/100,000) Trend Mizoram 38.8 37.9 Highest, stable Delhi 13.2 6.2 Rising Bangalore 10.5 4.8 Rising Chennai 9.9 3.7 Rising Mumbai 8.4 3.5 Moderate increase 3.2. Tobacco smoking as a dominant risk factor: Figure. 3: Causes of Lung Cancer in India Multiple case–control studies published between 2018 and 2023 reinforce that tobacco use remains the single largest contributor to lung cancer in India [16]. Unlike Western countries, bidi smoking is more prevalent in rural and semi-urban populations, and it carries greater carcinogenic potential. Odds ratios (ORs) for bidi smoking range between 4.2 and 8.3, compared to 2.0–5.0 for cigarette smoking [16]. This highlights the disproportionate risk faced by lower socioeconomic groups, who also have less access to healthcare services. Additionally, smokeless tobacco, though not directly associated with lung cancer, has been noted as a co-factor in populations with high tobacco burden. The dual use of smokeless and smoked tobacco increases risk through additive carcinogenic pathways. Despite the Cigarettes and Other Tobacco Products Act (COTPA) amendments and public health campaigns, enforcement remains weak, particularly in northern and northeastern states. ISSN: 2583-9209; SJCSIT Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||7 3.3. Biomass fuel and indoor air pollution: Household air pollution (HAP) from biomass fuels is another significant contributor, particularly among women in rural households. Studies from North India published in 2019 and 2021 report that long-term exposure to cooking smoke from wood, crop residues, and dung cakes doubles or triples lung cancer risk [15]. Women exposed to biomass smoke for over 15 years have ORs ranging from 1 .8 to 3.0. Despite national programs promoting liquefied petroleum gas (LPG) under the Pradhan Mantri Ujjwala Yojana (PMUY), adoption remains incomplete. Many households continue using biomass fuels due to affordability and supply chain challenges. Consequently, women and children remain disproportionately affected. 3.4. Outdoor Air Pollution (PM2.5 and NOx): Air pollution in urban India has emerged as a modern epidemic. Delhi and other metropolitan regions consistently rank among the world’s most polluted cities. Long-term exposure to PM2.5 levels exceeding World Health Organization (WHO) limits has been shown to increase lung cancer risk by 1.5–2.0 times [16]. Recent cohort studies estimate that air pollution accounts for 8–12% of lung cancer cases in major Indian cities. Vehicle emissions, industrial discharges, and construction dust are the major contributors. Unlike tobacco, which primarily affects men, air pollution increases risk in both genders and across socioeconomic strata. This makes it a pressing environmental and health policy issue. 3.5. Histological shifts in lung cancer: Historically, squamous cell carcinoma dominated the histological spectrum of Indian lung cancer. However, multiple hospital-based studies between 2018 and 2025 have confirmed a clear shift toward adenocarcinoma [21]. A ten-year cohort analysis from the all India Institute of Medical Sciences (AIIMS), published in 2020, found adenocarcinoma in 34% of patients, surpassing squamous carcinoma at 28.6% [18]. By 2022, multicenter studies across Delhi, Mumbai, and Bangalore reported adenocarcinoma rates of 38–40% [21]. Squamous carcinoma accounted for 25–30%, while small cell lung cancer remained stable at 10–15% [17]. This transition reflects global trends and is likely driven by multiple factors: a shift from unfiltered bidis to filtered cigarettes, increasing biomass and air pollution exposure, and improved diagnostic accuracy through immunohistochemistry and molecular testing. 3.6. Molecular epidemiology: EGFR, ALK, and ROS1: Molecular profiling has become increasingly common in India, particularly at tertiary care centers. Among non-small cell lung cancer (NSCLC) patients, Epidermal Growth Factor Receptor (EGFR) mutations are found in 23–30% of cases [18, 19]. This prevalence is higher than in Western populations (~10–15%) and closer to East Asian rates. Anaplastic Lymphoma Kinase (ALK) rearrangements are detected in approximately 10–12% of adenocarcinoma cases [20], while ROS1 Volume-3|| Issue-3||2025||Sept-Dec ISSN: 2583-9209; SJCSIT Vanita et al., Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||8 rearrangements occur in 2–3%. These findings are clinically important because they enable the use of tyrosine kinase inhibitors (TKIs), which significantly improve survival in mutationpositive patients. However, access to molecular testing remains limited due to cost barriers. Many patients in tier-2 and tier-3 cities remain undiagnosed, and those who test positive often cannot afford targeted therapy. This disparity reflects India’s dual healthcare system, where advanced technologies coexist with limited affordability. 3.7. Stage at diagnosis and survival outcomes: Despite advances in diagnostics, more than half of Indian patients continue to present with advanced disease. Hospital audits between 2018 and 2023 consistently report that over 50% of patients are diagnosed at Stage IV, with only 20% detected at potentially curable Stages I–II [17]. Median survival remains poor at 10–12 months for non-small cell lung cancer (NSCLC) [22], with slightly better outcomes in patients receiving targeted therapies. Small cell lung cancer (SCLC) continues to carry a dismal prognosis, with median survival less than 8 months [22]. The lack of systematic screening programs is a major factor. Low-dose computed tomography (LDCT) screening, which is validated internationally, has not been implemented at the national level in India. Diagnosis is often delayed due to symptom overlap with tuberculosis and chronic obstructive pulmonary disease (COPD). Figure. 4: Stage at Diagnosis of Lung Cancer in India 3.8. Financial and socioeconomic burden: One of the most striking findings from recent studies is the catastrophic financial impact of lung cancer treatment. Targeted therapies and immunotherapies cost ₹60,000–100,000 per month, far beyond the reach of most Indian households. Multiple reports from 2020 to 2023 describe patients selling assets, taking loans, or abandoning treatment due to cost. Even when patients initiate therapy, many discontinue prematurely because of financial stress. This “financial toxicity” has emerged as a critical determinant of survival outcomes, alongside clinical and biological factors. 4. Data and methodology: ISSN: 2583-9209; SJCSIT Scienxt Journal of Computer Science & Information Technology Scienxt Center of Excellence (P) Ltd SJCSIT||9 4.1. Data Sources This study synthesized data from multiple Indian sources between 2018 and 2025 to provide a comprehensive overview of lung cancer trends, causes, and implications. The primary data sources included: 1. Population-Based Cancer Registries (PBCRs): Managed by the Indian Council of Medical Research (ICMR), these registries cover over 30 geographic locations. Updates between 2019 and 2022 provided incidence rates stratified by region, gender, and age [1]. For example, Mizoram reported AARs of ~38.8 per 100,000 in men and ~37.9 in women in 2020–2021. 2. Hospital-Based Cancer Registries (HBCRs): Institutions such as AIIMS (All India Institute of Medical Sciences) in Delhi, Tata Memorial Hospital in Mumbai, and PGIMER (Postgraduate Institute of Medical Education and Research) in Chandigarh contributed detailed histological and clinical data. Between 2018 and 2023, these registries collectively reported more than 20,000 lung cancer cases [17, 18]. 3. Case–Control Studies: Recent Indian studies (2018–2023) provided odds ratios (ORs) for risk factors such as bidi smoking (OR 4.2–8.3), cigarette smoking (OR 2.0–5.0), biomass fuel exposure (OR 1.8–3.0), and air pollution (OR 1.5–2.0) [16]. 4. Molecular Epidemiology Studies: Multicenter analyses from Delhi, Mumbai, and Bangalore documented EGFR mutations in ~23–30% of non-small cell lung cancer (NSCLC) patients [19], ALK rearrangements in ~10–12% [20], and ROS1 rearrangements in ~2–3%. 5. Socioeconomic and Financial Studies: Surveys published between 2020 and 2023 examined the cost of lung cancer treatment. The median monthly cost for targeted therapy was ₹60,000– 100,000, with ~65% of families reporting catastrophic health expenditure. 4.2. Inclusion criteria and data cleaning To ensure methodological consistency, the following inclusion criteria were applied: only studies conducted in India between 2018 and 2025, peer-reviewed journal publications, NCRP reports, or official HBCR datasets, and studies that reported incidence rates, odds ratios, survival outcomes, or treatment costs. We excluded case reports, global studies without Indian-specific data, or studies published before 2018. Data were harmonized by converting incidence rates to age-adjusted per 100,000 population, standardizing odds ratios across studies, and normalizing cost data to 2023 Indian Rupees (₹). 5. Results and analysis: This section presents the consolidated findings from the literature review, highlighting key statistics and trends. Table. 2: Major risk factors and odds ratios (2018–2025)