Dr. Chinmay Jani on Air Pollution and Lung Cancer

Author(s): Scott Douglas Jacobsen

Publication (Outlet/Website): The Good Men Project

Publication Date (yyyy/mm/dd): 2025/02/14

Dr. Chinmay Jani is a clinical fellow in hematology and oncology at the Sylvester Comprehensive Cancer Center, University of Miami. With a strong medical background, he has published extensively on topics like lung cancer trends, COVID-19, and precision medicine. His work emphasizes global risk factors, such as tobacco, air pollution, and asbestos, impacting cancer mortality. Dr. Jani has completed his medical school at Gujarat University, ranking among the top in his medical school class, and completed his Internal Medicine residency and chief residency at Mount Auburn Hospital and Harvard Medical School. Fluent in multiple languages, he is an active member of global medical societies and a proponent of tailored public health policies and precision oncology. Jani discussed research on lung cancer mortality trends, focusing on tobacco, air pollution, and asbestos as key risk factors. Tobacco-related lung cancer deaths have declined globally but remain significant, with gender disparities evident. Air pollution, particularly PM2.5, has become a growing concern, showing increased mortality rates in countries like China. In contrast, household air pollution has decreased due to cleaner energy initiatives. Asbestos exposure continues to impact lung cancer rates, especially in the U.S., where mortality rates are double the global average. Dr. Jani emphasized the importance of targeted policies, public awareness, and precision medicine in addressing these challenges. For more information, see here.

Scott Douglas Jacobsen: We are here with Dr. Chinmay Jani, a clinical fellow in hematology and oncology at the Sylvester Comprehensive Cancer Center at the University of Miami Health System. First question: What were the primary objectives of the Sylvester Comprehensive Cancer Center on lung and related cancer trends study? 

Dr. Chinmay Jani: The primary objective of our study was to investigate risk factor-associated mortality trends for lung cancer. We focused on three main risk factors: tobacco, air pollution, and asbestos. We also stratified air pollution into household air pollution and PM2.5, fine particulate matter pollution. We analyzed how these trends have evolved over the past two or three decades in the ten most populous countries in the world. 

Jacobsen: Why work on the ten most populous countries?

Jani: That’s a great question. We have a robust global oncology department here at the University of Miami, led by Dr. Gilberto Lopes, also the senior author of this paper. He directs the department and guided us in conducting a global analysis of lung cancer mortality trends.

There are various ways to approach this type of research. Still, we selected the ten most populous countries because they account for a significant proportion of the global population. These countries also represent diverse geopolitical, economic, and environmental factors. For example, they include developed nations like the United States, developing countries like India and Pakistan, and regions like Nigeria in Africa. This selection provides a comprehensive perspective on how these countries, which substantially influence global economics, policies, and climate, manage lung cancer risk factors and mortality trends.

Jacobsen: How have tobacco-related lung cancer mortality rates evolved globally?

Jani: Overall, lung cancer mortality rates have been decreasing globally. 1990 the global mortality rate was approximately 27.3 deaths per 100,000 population. By 2019, this figure had declined to 25.2 per 100,000 population. However, I want to clarify that our study focused specifically on lung cancer mortality rates, not incidence rates.

Gender-based trends reveal an interesting disparity. Among males, mortality rates have significantly decreased, dropping from approximately 45 to 37 deaths per 100,000 population—a substantial reduction. Conversely, standardized mortality rates among females have increased, rising from 13 to 15 deaths per 100,000 population. While female mortality rates remain less than half of male rates, the upward trend among females contrasts sharply with the steady decline observed in males.

For the tobacco-related findings, I want to highlight that, proportionally, tobacco has had a significant impact on lung cancer mortality. Our study included trachea, bronchus, and lung (TBL) cancer mortality. Still, for simplicity, we often refer to these as lung cancers in this study.

In the 1990s, tobacco accounted for approximately 72% of lung cancer mortality globally, which means nearly three-fourths of the cases were attributed to it. By 2019, this figure decreased to 66%, which is still two-thirds. Over the past three decades, significant strides have been made in tobacco control policies. For example, we see fewer tobacco advertisements, smoking bans in public places in many countries, and health organizations refusing sponsorship from tobacco companies.

Despite these efforts, the reduction from 72% to 66% shows slow progress. This indicates the need for continued and intensified efforts to address this modifiable risk factor. Reducing tobacco use could lead to a substantial decrease in lung cancer mortality.

When we look at gender-specific trends, for males, the proportion of tobacco-related lung cancer mortality decreased from 81% to 77%, which is still above three-fourths. For females, it decreased from 49% to 44%, meaning almost half of the lung cancer mortality in females is still linked to tobacco. If we can further reduce tobacco use, we could significantly lower lung cancer mortality worldwide.

We also want to highlight that tobacco consumption habits are different in different parts of the world. For example, in Indian sub-continent countries, tobacco is usually consumed along with betel nut, which can have its own side effects and increase cancer risk.

Jacobsen: What role does asbestos exposure play in TBL cancer deaths? How do the U.S. mortality rates compare to global averages despite the ban on asbestos?

Jani: Our study yielded some very interesting findings on asbestos. Initially, we focused on tobacco and air pollution as key risk factors for lung cancer mortality. Later, we delved deeper into asbestos-related mortality, particularly after presenting our preliminary findings at the April AACR (American Association for Cancer Research) conference. Around the same time, a new law was enacted in the U.S. banning asbestos, which prompted us to analyze this data further.

To our surprise, lung cancer mortality attributed to asbestos in the U.S. is double the global average. For example, asbestos-related lung cancer mortality in U.S. males is approximately 11.9 per 100,000 population. In contrast, the global average is only 5.1 per 100,000.

Globally, some countries, such as India, China, Indonesia, and Pakistan, are seeing an increase in asbestos-related mortality. While the U.S. has seen significant reductions in asbestos exposure and related mortality rates due to stricter regulations, the current rate remains much higher than the global average, which is concerning. These findings underscore the need for continued vigilance and global efforts to eliminate asbestos use and exposure.

The numbers I’ve mentioned are specific to males, as they tend to have higher exposure to asbestos due to occupational risks. This disparity highlights the need for targeted policies to address these risk factors more effectively.

Jacobsen: So, male patterns are distinct.

Jani: There could be multiple reasons why this is happening. While our study did not establish causality, reviewing the literature and past studies provides some insights into the trends. The cumulative effect of asbestos exposure on health is far greater than initially expected.

Even though significant bans have been implemented, and asbestos has not been widely used for a long time, numerous earlier policies have been limiting its use. However, the cumulative exposure over decades has left a lasting impact. It is important to note that asbestos-related cancers often have a latency period of five to ten years or even longer before they manifest. Once lung cancer develops, the progression to mortality can also take years. This extended timeline means that the cumulative effects of past asbestos exposure are still evident today.

Jacobsen: How does the integration of molecular insights and precision medicine address lung cancer risk factors?

Jani: Another factor to consider is that although asbestos is no longer widespread, significant amounts remain in the environment. It is in older infrastructure, including houses, pipes, and other materials. These residual sources continue to contribute to lung cancer mortality, even though direct usage has declined.

Jacobsen: It’s an ambient leftover from prior infrastructure projects.

Jani: Exactly. That’s a very accurate way to describe it. 

Jacobsen: What are the key findings regarding the impact of air pollution, particularly PM 2.5, on global TBL cancer mortality?

Jani: We divided the data on air pollution into two parts. The first was ambient air pollution, particularly PM2.5, which refers to fine particulate matter pollution that is inhaled and contributes to lung cancer. The second was household air pollution caused by the use of solid fuels.

A positive finding from our study is that lung cancer mortality caused by household air pollution has significantly decreased across all countries and for both males and females. This trend is encouraging, especially in developing countries where solid fuels are traditionally used extensively. This reduction reflects the success of improved household fuel policies and cleaner energy initiatives.

However, the situation is quite different regarding ambient PM2.5 pollution. Globally, the impact of ambient air pollution has increased. The highest increase has been observed in China, where lung cancer mortality due to ambient particulate matter has risen dramatically. For instance, the rate of males has increased from 5.4 to 13.6 per 100,000 population—an almost 2.5-fold rise. For females, the rate has increased from 1.69 to 5 per 100,000 population, nearly tripling as well.

The data also shows a 25% increase in global lung cancer mortality attributable to ambient air pollution, making it the second-largest modifiable risk factor for lung cancer after tobacco. These findings indicate a pressing need for policies addressing ambient particulate matter. While significant efforts have been made to reduce tobacco-related lung cancer mortality, air pollution now demands similar attention.

We must focus on understanding the molecular mechanisms by which air pollution contributes to lung cancer and work on preventive measures to curtail its impact. By addressing this modifiable risk factor, we can significantly reduce global lung cancer mortality.

Jacobsen: How does the integration of molecular insights and precision medicine address lung cancer risk factors?

Jani: As we deepen our understanding of lung cancer, it has become clear that not all lung cancers behave the same way. Historically, the primary classification was between non-small cell lung cancer, such as adenocarcinoma and squamous cell carcinoma. With advancements, particularly the introduction of immune checkpoint inhibitors, we’ve learned that while some patients respond exceptionally well to these treatments, others do not.

This has prompted numerous studies to investigate the reasons for these differences. We have evidence that patients with certain targetable mutations respond differently to specific treatments. For instance, around seven or eight years ago, the NCCN (National Comprehensive Cancer Network) guidelines primarily recommended chemotherapy for stage four lung cancer, with immune checkpoint inhibitors just starting to emerge and only a few targeted therapies available.

Today, the landscape has changed dramatically. We now have treatments targeting mutations such as EGFR, ALK, ROS1, HER2, etc. This evolution highlights that while all these cases are classified as lung cancer, they behave differently and require different treatments.

This study could contribute to understanding how different risk factors, like tobacco or air pollution, might influence specific molecular alterations in lung cancer. Future research could explore whether these risk factors affect molecular changes differently and how this knowledge could guide precision medicine or precision oncology, tailoring treatments to individual patients based on their risk factors and molecular profiles. For instance, studying the impact of air pollution on molecular changes in lung cancer could open up new avenues for targeted therapies.

Jacobsen: What gaps exist in current lung cancer screening guidelines?

Jani: That’s an excellent question and an ongoing discussion and research area. The current U.S. Preventive Services Task Force (USPSTF) guidelines, which are widely used in the U.S. and referenced in other countries, focus primarily on smoking as the main risk factor for lung cancer screening. For a patient to qualify for screening and receive insurance reimbursement, they must have at least a 20-pack-year smoking history or have quit smoking within the past 15 years.

In our study, we found that 66% of lung cancer deaths were associated with smoking. However, this leaves 34% of cases unexplained by smoking history. Among females, more than 50% of lung cancer deaths occur in patients without tobacco as a risk factor. These individuals are not currently included in screening programs based on existing guidelines. Similarly, other risk factors, such as asbestos exposure or air pollution, are not yet incorporated into screening criteria or insurance reimbursement policies.

We need more research to refine risk factor models for lung cancer screening to address these gaps. Expanding screening guidelines to include additional risk factors and increasing the uptake of lung cancer screening would help diagnose cases earlier and improve outcomes.

Jacobsen: What policy measures and public awareness strategies are suggested by the researchers to address the increasing cancer risks?

Jani: Policy measures and public awareness strategies are essential to address cancer risks.

1. Tobacco Control Policies: While progress has been made, stronger global efforts are needed to reduce tobacco use further. Policies should focus on stricter advertising bans, increased taxation, and broader implementation of smoke-free public spaces.
2. Air Pollution Regulations: Air pollution is becoming the second-largest modifiable risk factor for lung cancer. Governments must enforce stricter regulations on industrial emissions, promote cleaner energy sources, and improve public transportation to reduce reliance on fossil fuels.
3. Asbestos Ban and Cleanup: Although asbestos use is banned in many countries, legacy asbestos remains in older buildings and infrastructure. Efforts can be made for large-scale cleanup projects and raise awareness about the risks of asbestos exposure.
4. Expanding Screening Guidelines: Screening criteria must include non-smoking-related risk factors like air pollution and asbestos. Policymakers should allocate resources to refine screening models and ensure insurance coverage for these expanded criteria.
5. Public Awareness Campaigns: Education campaigns should inform the public about smoking, air pollution, and asbestos exposure risks. Outreach efforts should focus on high-risk populations, particularly in developing countries, where awareness may be lower.
6. Research Funding: Increased funding for research on lung cancer risk factors, molecular mechanisms, and precision medicine is critical. This will allow researchers to understand better how environmental and genetic factors interact and develop more effective treatments.
7. Global Collaboration: Cancer prevention strategies require international collaboration to share data, best practices, and resources. Addressing air pollution and tobacco use requires coordinated efforts across borders.

By implementing these measures and raising awareness, we can significantly reduce lung cancer risks and improve outcomes globally.

As I mentioned, the main policies that should be implemented include strengthening tobacco-related regulations and developing more targeted policies addressing air pollution and asbestos exposure. Understanding the associations between air pollution and lung cancer, particularly in developing countries like India and China, will enable policymakers to devise more effective strategies.

One simple example is related to burning waste in India. Over the past decade, the government of India has made tremendous efforts to increase awareness about the dangers of burning solid waste. While the use of solid fuels for cooking in households has significantly decreased, the practice of burning waste persists in certain areas. Although the government provides resources and alternatives, public awareness is still lacking.

Now that we have more evidence showing that these risk factors—like smoking, which causes not only lung cancer but also many other cancers—are detrimental, public awareness campaigns are crucial. If people become more informed, they are more likely to accept and comply with these policies. Creating awareness is, in my opinion, the priority. Once awareness is established, policies can be tailored to meet each country’s needs.

Jacobsen: Dr. Jani, thank you very much for your time today. I truly appreciate it.

Jani:  Thank you very much.

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