Flight attendants/pilots and cancer

A passenger jet on approach to Newark Liberty International Airport flies over the setting sun in Newark, N.J., March 27, 2019. (AP Photo/J. David Ake, File)

 From AP

Flight attendants and pilots are at the highest risk of dying from radiation-related cancers — even more than people who work with radioactive materials, according to a new study.

Cosmic radiation comes from space. Only a small amount reaches the Earth’s surface, but exposure is greater for people flying at high altitudes.

There’s been limited evidence from small studies suggesting that the exposure translates to higher cancer death rates among people who fly often — particularly pilots and flight attendants. The new study “brings important new evidence to bear on this question,” two Australian radiation experts who weren’t involved in the research wrote in an accompanying commentary.

The latest study, published Monday by JAMA Internal Medicine, used national data from more than 12 million death certificates that included information about occupations. The authors looked at death rates from cancers that are tied to radiation exposures, including leukemia, lymphoma, multiple myeloma, and cancers of the skin, breast, thyroid, prostate and central nervous system.

Among more than 500 occupations, flight attendants had the highest percentage of deaths from radiation-related cancers, and pilots were second, the researchers found. For those two occupations, the odds of dying were unusually high for each type of radiation-related cancer.

Neither group showed higher-than-normal death rates from cancers that aren’t tied to radiation exposure, noted the commentary writers, Catherine Olsen and Ken Karipidis. That fact “supports the hypothesis that occupational radiation exposure, rather than lifestyle or socioeconomic factors, underlies the observed excess,” they wrote.

The researchers found that flight attendants had about 50% higher odds of dying from a radiation-related cancer than the general working population, and pilots had about 36% higher odds.

In terms of absolute risk, about 6.9% of flight attendant deaths were from these cancers — roughly 1 in 14. Among pilots, it was 6.7%. For the general working population, it was 5%, said the study’s first author, Dr. Vishal Patel of Harvard Medical School.

The authors acknowledged some limitations in their study. They do not know how much exposure each flight attendant and pilot got in the air or from other sources. It’s also possible occupations were misclassified on some death certificates.

They also could not account for another possible contributor specific to the professions: Cancer risk can be worsened by frequent disruption of the body’s internal clock, which can be affected by jet lag, crossing time zones and irregular work schedules.

The Federal Aviation Administration has acknowledged that aircrews are exposed to ionizing radiation, but the government does not set federal dose limits or require monitoring, the authors noted.

“You can’t manage an exposure you’ve decided not to measure,” Patel said in an email.

Sara Nelson, who leads a union representing 55,000 flight attendants, said the report reinforces that radiation exposure needs to be taken seriously, as the union has suggested for years.

“The risk is known, but crew are not educated or informed. And, no one is taking responsibility,” said Nelson, president of the Association of Flight Attendants-CWA.

Annual skin examinations may be warranted for all people working on high-altitude flights, and women in those jobs may want to get mammograms earlier or more frequently, Olsen and Karipidis wrote. Doctors who care for pilots and flight attendants also should have a “heightened index of suspicion” for cancer when evaluating these patients, they said.

Air travel adds to greenhouse gas emissions.  It's bad for the world.  Now it turns out it's bad for the people who fly us.

And Mars's atmosphere is only 0.6% as dense as the Earth's.  The cancer risk will be much higher there, even from shorter exposures.

 

Nuclear power stations and cancer

From Harvard Graduate School of Arts and Sciences
By Dr Yazan Alwadi

Nuclear power accounts for 18 to 20 percent of electricity generated in the United States. In some places, the share is much greater—over half the energy generated in Illinois, for instance, the country’s sixth-largest state. As demand rises sharply, particularly from AI data centers, the federal government has increased funding, loans, and tax incentives in an effort to increase nuclear capacity, extend operations of existing reactors, and restart retired ones.

Although public support for nuclear energy has surged in recent years, opposition remains strong. The most common reason? Safety concerns. And they may be valid, according to population health scientist Yazan Alwadi, who received his PhD from the Harvard Kenneth C. Griffin Graduate School of Arts and Sciences in February 2026, months after receiving a master’s degree in biostatistics in November 2025. Now a post-doctoral researcher at the Harvard T.H. Chan School of Public Health, Alwadi’s work uncovers a link between cancer and proximity to nuclear power plants.

Too Close for Comfort?

In the lab of Petros Koutrakis, Akira Yamaguchi Professor of Environmental Health and Human Habitation at the T.H. Chan School, Alwadi investigated whether living close to nuclear facilities impacts a population’s incidence of developing or dying from cancer. The work was motivated by a call from the Department of Public Health in Plymouth County, Massachusetts. Community members were concerned about rising cancer cases, and some wondered whether Plymouth’s Pilgrim Nuclear Power Station, decommissioned in 2019, might have contributed to the uptick.

“We get emails from families, saying that big percentages of people they know get cancer. But of course, these are anecdotal, so it needs hard science and statistical evidence to see if that actually happens or not,” Alwadi says.

As an environmental epidemiologist, Alwadi decided to investigate. “We wanted to know, are we going to find an association between the proximity to plants and cancer or not?” Alwadi says. Regardless of the outcome, he would share his findings.

Alwadi conducted a longitudinal ecological study, comparing Massachusetts zip codes’ proximity to the seven nuclear facilities in the vicinity of the state with that zip codes’ cancer incidence over time (provided by the state’s cancer registry). He used proximity as a proxy for exposure because it encompasses multiple routes of dispersal, like air and water. “We know that distance is a proxy for most [exposure routes]. It's not perfect for any one of them, but a proxy for most,” Alwadi says.

Alwadi discovered a strong association between cancer incidence and proximity to plants for populations over 55 years old living within 5 km of a nuclear power plant. For example, women ages 65-74 living two km away from a nuclear power plant had 2-times higher relative risk of cancer, and men in this age group had 1.75-times higher risk.

To determine whether these results were more broadly generalizable to the United States, Alwadi conducted a similar study comparing nuclear power plant proximity to county-level data on cancer mortality from the US Centers for Disease Control. “We felt that doing [the analysis] nationally would give us enough statistical power to depict effects if they truly exist,” says Alwadi. He discovered that the association he observed in Massachusetts held at the national level, too. “We observe the same association, similar values, same decline of risks with distance across different aggregations, zip codes versus counties . . . for cancers of interest.”

Koutrakis says that his advisee’s research is notable because it is the first series of studies to systematically demonstrate associations between residential proximity to nuclear power plants and cancer outcomes across multiple settings using large, population-based datasets. “This work fills a critical gap in the literature by providing large-scale, systematic evidence on a question that has remained unresolved for decades.”

“[Alwadi’s] results—which suggest that those living close to commercial plants face elevated cancer risks due to emissions from routine operation—are provocative and highly controversial,” says John Evans, retired professor of environmental health at the T.H. Chan School and a co-author on the study. “They are provocative because, since the inception of commercial nuclear power, it has been assumed that routine operations posed essentially no risk and that for public health the relevant issue was the possibility of accidental releases, like those at Chernobyl and Fukushima.”

Importantly, while the study shows a robust association between nuclear plant proximity and cancer, the study’s design cannot determine whether that relationship is causal. “Although these are ecological designs that do not establish causality and are very hard to infer causality from their evidence, the systematic results and the consistency of the findings are exactly what you'd expect to find if a true underlying causal effect existed,” says Alwadi. By systematically demonstrating an association, Alwadi’s discovery provides the impetus for more detailed research to understand the nature of the link between nuclear power plants and cancer.

It might just be an association not causation, and we don't know quite how the incidence of cancer is increased, but it seems very plausible, doesn't it? 

Read about Dr Alwadi's path to Harvard in the second half of the article.

Red & processed meat & cancer

 From the American Cancer Society

What are red and processed meats?

Red meat includes beef, pork, veal, lamb, mutton, and goat. These meats might be fresh, ground, or frozen. Red meat is a probable carcinogen.

Processed meat has been treated through smoking, curing, salting, or fermentation. This includes bacon, ham, deli meat, sausage, and hot dogs. Processed meat is a known carcinogen.

Carcinogens are things that can cause cancer.

Do red and processed meats cause cancer?

Eating red and processed meat is linked to a higher risk of colorectal cancer. These meats may also increase the risk of breast, pancreatic, prostate, and stomach cancer, but more research is needed.

Red meat has heme iron, which has been shown to increase the risk of DNA damage and cancer. The risk of cancer may increase further when red meat is cooked at a high temperature, like grilling, frying, or broiling. These cooking methods create compounds found to cause DNA changes in lab studies. Processed meat contains nitrates and nitrites which, can damage DNA in cells and lead to increased cancer risk.

Both red and processed meat are high in saturated fats. Eating a lot of saturated fat can cause chronic inflammation and increase your risk of cancer. It can also increase your risk of having excess body weight, which can heighten your risk of cancer and other chronic diseases.

How much red and processed meat can I safely eat?

It is not known if any amount of red or processed meat can be eaten without increasing your risk of cancer.

The American Cancer Society guideline recommends choosing proteins like poultry, fish, or plant-based proteins instead of red meat most of the time. It’s best to avoid processed meat. If you do choose to eat processed meat, you are encouraged to do so sparingly.

The American Institute for Cancer Research and the American Society of Clinical Oncology recommend avoiding all processed meat and eating no more than 18 ounces (3 – 4 servings) of red meat each week to reduce cancer risk.

What can I eat instead of red and processed meat?

There are many sources of protein that can be eaten instead of red and processed meat. Some good options are:

• Poultry, such as chicken and turkey
• Fish and other types of seafood
• Plant-based sources of protein like beans, peas, lentils, nuts, soy, and mushrooms. 
• Low-fat dairy products like milk, yogurt, and kefir. 

Interesting.  I mean, this isn't Uncle Gazza down the pub, or an earnest leaflet distributor on the high street.  It's the American Cancer Society.   But, actually, the evidence has been around for 40 years or longer.  I found this chart online after searching my personal hard copy of Why You Don't Need Meat, which I bought in 1986, and which is a splendid book detailing everything you needed to know about eating meat, and why you shouldn't.

(Source)

Incidentally, a similar correlation exists for consumption of meat and heart disease.

Exercise better than drugs for cancer treatment

 From The Guardian

After five years, patients in an exercise regime had a 28% lower risk of recurrent or new cancers, and a 37% lower death rate. Photograph: amriphoto/Getty Images

Exercise can reduce the risk of cancer patients dying by a third, stop tumours coming back and is even more effective than drugs, according to the results of a landmark trial that could transform health guidelines worldwide.

For decades, doctors have recommended adopting a healthy lifestyle to lower the risk of developing cancer. But until now there has been little evidence of the impact it could have after diagnosis, with little support for incorporating exercise into patients’ routines.

Now a world-first trial involving patients from the US, UK, Australia, France, Canada and Israel has found that a structured exercise regime after treatment can dramatically reduce the risk of dying, the disease returning or a new cancer developing.

The results were presented in Chicago at the American Society of Clinical Oncology (Asco) annual meeting, the world’s largest cancer conference, and published in the New England Journal of Medicine.

For the first time in medical history, there was clear evidence that exercise was even better at preventing cancer recurrence and death than many of the drugs currently prescribed to patients, one of the world’s top cancer doctors said.

Dr Julie Gralow, the chief medical officer of Asco, who was not involved in the decade-long study, said the quality of its findings was the “highest level of evidence” and would lead to “a major shift in understanding the importance of encouraging physical activity during and after treatment”.

Patients who began a structured exercise regime with the help of a personal trainer or health coach after they completed treatment had a 37% lower risk of death and a 28% lower risk of recurrent or new cancers developing, compared with patients who received only health advice, the trial found.

Asked to put the effect of exercise on cancer patients’ outcomes into context, Gralow said: “We titled [the session it was presented in] As Good as a Drug. I would have retitled it Better than a Drug, because you don’t have all the side-effects.” 

“It’s the same magnitude of benefit of many drugs that get approved for this kind of magnitude of benefit – 28% decreased risk of occurrence, 37% decreased risk of death. Drugs get approved for less than that, and they’re expensive and they’re toxic.”

“When I started three decades ago it was still the era where we’d be gentle and say, don’t overdo yourself when you’re on chemo. We’ve reversed that,” she added. “I would say [exercise is] better than a drug.”

In the trial, researchers enrolled 889 colon cancer patients between 2009 and 2023. Most (90%) had stage three disease. Patients were randomly assigned to take part in a structured exercise programme (445) or to just receive a healthy lifestyle booklet (444).

Those in the exercise group worked with a personal trainer twice a month for coaching sessions and supervised exercise sessions, and later once a month, for a total of three years.

The exercise group were coached and supported to help them achieve set exercise goals. Their weekly target was the equivalent of three to four walks of between 45 and 60 minutes, but patients could choose how they got more active. Some went kayaking or skiing, for instance.

After five years, patients in the exercise group had a 28% lower risk of recurrent or new cancers than those in the other group. After eight years, the same patients also had a 37% lower risk of dying than those just handed the healthy lifestyle booklet.

“After completing surgery and chemotherapy, about 30% of patients with high-risk stage two and stage three colon cancer will eventually experience recurrence of their disease,” said the study’s lead author, Dr Christopher Booth, of Queen’s University in Kingston, Canada. “As oncologists, one of the most common questions we get asked by patients is ‘what else can I do to improve my outcome?’ 

 “These results now provide us with a clear answer: an exercise programme that includes a personal trainer will reduce the risk of recurrent or new cancer, make you feel better and help you live longer.”

Obesity links to prostate cancer confirmed

From New Atlas

Obesity increases a man’s risk of dying from prostate cancer, according to a massive new study by researchers in the UK, however, the causal mechanisms underpinning the link are not yet clear.

Prostate cancer is one of the most common forms of cancer to be detected in men. It is a slow-growing form of cancer, so patients can live many years after diagnosis. In fact, many patients diagnosed with prostate cancer ultimately die of other causes before the cancer develops enough to cause its own problems.

Because of the prevalence of this kind of cancer, researchers have been working to understand what factors may contribute to the development of more aggressive types of prostate cancer. Aurora Perez-Cornago, lead on the new research from the University of Oxford, said knowing the risk factors for fatal prostate cancer could help patients avoid certain damaging lifestyle practices.

“Knowing more about factors that increase the risk of prostate cancer is key to preventing it,” said Perez-Cornago. “Age, family history and black ethnicity are known risk factors but they are not modifiable, and so it is important to discover risk factors that it is possible to change.”

Excess body fat has previously been linked to higher rates of fatal prostate cancer. This new research set out to get a clearer insight on the association between body weight and prostate cancer by conducting a meta-analysis of 19 prior studies, including data from more than 2.5 million men.

The overall finding affirmed prior suspicions, with higher volumes of body weight linked to higher rates of fatal prostate cancer. Quantifying that increased risk the research found for every five point rise in body mass index (BMI), a person increased their risk of dying from prostate cancer by 10 percent.

The association between body weight and fatal prostate cancer was independent of where a person’s body weight was concentrated. But the researchers did calculate a seven percent increase in risk of dying from prostate cancer for every 10-cm (3.9-in) increase in waist circumference. Looking at UK data the study estimated around 1,300 fewer people would die from prostate cancer every year if the average BMI of men dropped by five points.

Perez-Cornago said the link between body weight and fatal prostate cancer may be clear but it still is not known what could be driving the association. It is plausible to suggest higher volumes of body fat may be driving the progression of prostate cancer. In fact, a 2018 study did hypothesize a mechanistic link between dietary fat and the metastatic progression of prostate cancer.

But the researchers also indicate other factors are likely playing a role, including differences in cancer detection between obese men and those with a healthy weight. Prostate-specific antigen (PSA) concentrations in blood samples, for example, can be lower in subjects with high BMI, meaning cancers may be detected at later stages leading to worse outcomes.

“More research is needed to determine if the association is biologically driven or due to delays in detection in men with higher adiposity,” said Perez-Cornago. “In either case, our latest results provide another reason for men to try to maintain a healthy weight.”

The new study was published in BMC Medicine.

Source: The European Association for the Study of Obesity

Wegovy dramatically cuts cancer risk

From The Guardian

Weight-loss drugs offer a new weapon in the global fight against cancer, with “enormous potential” to [both] prevent new cases and shrink tumours, doctors said as research showed the jabs can cut the risk of developing the disease by a fifth.

Blockbuster injections such as Wegovy [Ozempic] have revolutionised the treatment of obesity, and recently been approved for use in other areas of medicine, including reducing the risk of heart attacks, strokes and cardiovascular-related deaths.

Now experts say they increasingly believe weight-loss drugs could play a big role in preventing and treating cancer, the second leading cause of deaths globally.

A study presented at the world’s largest cancer conference found patients taking the drugs were 19% less likely to develop 13 obesity-related cancers, including ovarian, liver, colorectal, pancreatic, bowel and breast cancer.

The research involving 34,000 people, led by the Case Western Reserve University in Ohio, also found patients were half as likely to die over 15 years compared with patients not taking the jabs, also known as GLP-1 receptor agonists (RA).

The study co-authors, Dr Cindy Lin and Dr Benjamin Liu, said: “Our findings are significant in that they could change the paradigm of obesity management by suggesting early intervention with GLP-1 RAs could delay or prevent obesity-related cancer development.” There could be “multiple” ways in which the drugs cut the risk of cancer – not just by helping people to lose weight, they added.

A second study published at the American Society of Clinical Oncology (ASCO) annual meeting suggested weight-loss drugs could reduce the risk of cancer coming back in breast cancer patients – and boost their prospects of long-term survival. Researchers from Memorial Sloan Kettering Cancer Centre in New York said the jabs could cut the risk of cancer recurrence and be a “new tool” against the disease.

A third paper released at ASCO and led by Yale University, also looking at breast cancer patients, suggested taking weight-loss drugs reduced the chances of the disease returning.

Speaking in Chicago at ASCO, Dr Mitchell Lazar, the director of the institute for diabetes, obesity and metabolism at the University of Pennsylvania School of Medicine, said: “GLP-1 based therapies are highly effective at producing weight loss, and thus one of the fundamental mechanisms by which they improve cancer outcomes is via the impressive weight loss that they produce.

“Obesity is a risk factor for nearly all cancers, in both men and women. Thus the revolution in the medical treatment of obesity has enormous potential to prevent new cancers, reduce the severity and growth rate of existing tumours, and synergise with new cancer-specific therapies.”

Dr Jennifer Ligibel, a senior physician at Dana-Farber Cancer Institute who was not involved with the studies, said: “These are exciting, preliminary findings of a link between use of GLP-1 RAs and cancer risk.” They added to previous work suggesting the drugs could reduce cancer risk, she added.

A study published last December showed they were associated with a 50% reduced risk of bowel cancer in people with type 2 diabetes. “Individuals with diabetes who were prescribed a GLP-1 RA had a lower risk of colorectal cancer as compared with individuals who were not prescribed one of these drugs,” Ligibel said.

Dr Julie Gralow, the chief medical officer of ASCO, said the evidence was not clear yet as to whether the potential benefits of weight-loss drugs in reducing cancer risk were just as a result of weight loss – or whether there were other, unknown factors at play.

Gralow, a world-renowned cancer expert who was named woman oncologist of the year in 2023, said she was absolutely certain the jabs would become a much greater focus of cancer prevention research in the future. “The more we can do to reduce the risk factors and prevent cancer, the better,” she added.

“I do think that there are so many potential and already proven health benefits to these drugs, that it would be icing on the cake if we saw that they were also reducing cancers.

“I am very hopeful about overall improvements in health from this class of drugs.”

Cancer Research UK’s chief clinician, Prof Charles Swanton, cautioned it was still “early days”. There have been suggestions the drugs could even raise the risk of certain cancers, although recent research on thyroid cancer and pancreatic cancer has cast doubt on those concerns.

“Well-designed prospective trials with randomised data will provide more clarity on the potential and safety of weight-loss drugs to lower people’s risk of cancer,” said Swanton.

One wonders what the antiscience and antivaxxers think about this.  Will the far right take us back to the middle ages, more than just socially?

Getting fitter can reduce prostate cancer by 35%

Aerobic exercise such as jogging, cycling or swimming can help protect against prostate cancer, a Swedish study has found. Photograph: The Guardian/Victoria Jones/PA

From The Guardian

Men can reduce their risk of prostate cancer by as much as 35% by doing a little more jogging, cycling or swimming, a study suggests.

Boosting cardiorespiratory fitness by only 3% over the course of a year was linked to a much lower chance of developing the disease. The findings prompted the researchers to encourage men to boost their fitness levels to help cut their prostate cancer risk.

“The more intensive activity, the lower the requirement for duration and frequency,” said the study’s co-author Dr Kate Bolam, of the Swedish School of Sport and Health Sciences in Stockholm. “Also, getting more muscles involved will have greater aerobic challenge on the cardiovascular system.

“Hence, activities that involve the lower body … brisk walking or jogging, hiking, activities that you are barely not able to keep up a conversation while doing … or that preferably also include both arms and legs are recommended for more significant effect.

“The trick is to challenge your cardiovascular system on a regular basis so it improves to match the requirements placed on it. It could even be line dancing if that gets your heart rate up and you have fun.”

The study did not set out how someone might accomplish a 3% increase in cardiorespiratory fitness. But Bolam said her advice would be “to think about activities that you think are enjoyable that raise your heart rate that you could add to your weekly routine”.

The Swedish study analysed data on the physical activity levels, height and body mass index (BMI) of 57,652 men, along with information on lifestyle and perceived health, and the results of at least two cardiorespiratory fitness tests.

Annual cardiorespiratory fitness measurements were expressed by the amount of oxygen the body uses while exercising as hard as possible. The men were divided into groups depending on this increasing by 3%, remaining stable, or falling by 3% each year.

During an average follow-up period of seven years, researchers found 592 men were diagnosed with prostate cancer. Those whose fitness had improved by 3% annually were 35% less likely to develop cancer compared with those whose fitness had declined.


The findings were published in the British Journal of Sports Medicine.

Worms to kill cancer cells

 

Naked Anisakis simplex and Anisakis simplex coated with hydrogel sheath containing fluorescence dye. Credit: Shinji Sakai

From SciTechDaily

James Bond’s famed quartermaster Q provided the secret agent with an unlimited supply of equipment and gadgets to aid him on his missions. Now, scientists from Japan have shown that they are equally adept in providing microscopic worms with a surprising variety of useful and protective components.

Researchers from Osaka University have discovered that microscopic, free-living worms known as nematodes may be coated with hydrogel-based “sheaths” that can be further customized to transport functional cargo.

Nematodes are tiny, free-living worms that normally inhabit soil or other environmental niches and, under certain circumstances, may enter the human body. Anisakis simplex, a marine-dwelling nematode that may colonize humans when consumed, has shown an odd liking for cancer cells.

“Anisakis simplex has been reported to sense cancer, potentially by detecting cancer “odor,” and to attach to cancerous tissues,” says Wildan Mubarok, first author of the study. “This led us to ask whether it could be used to deliver anti-cancer treatments directly to cancer cells within the human body.”

To investigate this possibility, the researchers first developed a system for applying hydrogel sheaths to nematodes by dipping them in a series of solutions containing chemicals that bind together to create a gel-like layer all over their surface. This process essentially custom-fits a suit about 0.01 mm thick to the worm in about 20 minutes.

“The results were very clear,” says Shinji Sakai, senior author of the study. “The sheaths did not in any way interfere with the worms’ survival and were flexible enough to maintain the worms’ motility and natural ability to seek out attractive smells and chemical signals.”

Next, the researchers loaded the sheaths with functional molecules and found that this protected the worms from ultraviolet light or hydrogen peroxide. What’s more, the sheaths could be loaded with anti-cancer agents that the nematodes, protected but unimpeded by their hydrogel armor, could transport and deliver to kill cancer cells in vitro.

“Our findings suggest that nematodes could potentially be used to deliver functional cargo to a range of specific targets in the future,” states Mubarok. Given the adaptability of the hydrogel sheaths, this worm-based delivery system holds promise not only for delivering anti-cancer drugs to tumor cells in patients, but it also has potential applications in other fields such as delivering beneficial bacteria to plant roots.

Reference: “Nematode surface functionalization with hydrogel sheaths tailored in situ” by Wildan Mubarok, Masaki Nakahata, Masaru Kojima and Shinji Sakai, 16 June 2022, Materials Today Bio.
DOI: 10.1016/j.mtbio.2022.100328

Lung cancer and air pollution

Study highlights danger urban populations face from air pollution. Photograph: Dan Kitwood/Getty

From The Guardian

Scientists have uncovered how air pollution causes lung cancer in groundbreaking research that promises to rewrite our understanding of the disease.

The findings outline how fine particulates contained in car fumes “awaken” dormant mutations in lung cells and tip them into a cancerous state. The work helps explain why so many non-smokers develop lung cancer and is a “wake-up call” about the damaging impact of pollution on human health.

“The risk of lung cancer from air pollution is lower than from smoking, but we have no control over what we all breathe,” said Prof Charles Swanton of the Francis Crick Institute, who presented the findings at the European Society for Medical Oncology conference in Paris on Saturday.

“Globally, more people are exposed to unsafe levels of air pollution than to toxic chemicals in cigarette smoke, and these new data link the importance of addressing climate health to improving human health.”

Smoking remains the biggest cause of lung cancer, but outdoor air pollution causes about one in 10 cases in the UK, and an estimated 6,000 people who have never smoked die of lung cancer every year. Globally, about 300,000 lung cancer deaths in 2019 were attributed to exposure to fine particulate matter, known as PM2.5, contained in air pollution.

However, the biological basis for how air pollution causes cancer has remained unclear. Unlike smoking or sun exposure, which directly cause DNA mutations linked to lung and skin cancer, air pollution does not cause cancer by triggering such genetic changes.

Instead, those with non-smoking lung cancer tend to carry mutations that are also seen in healthy lung tissue – small errors that we accumulate in our DNA throughout life and which normally remain innocuous.

“Clearly these patients are getting cancer without having mutations, so there’s got to be something else going on,” said Swanton, who is also Cancer Research UK’s chief clinician. “Air pollution is associated with lung cancer but people have largely ignored it because the mechanisms behind it were unclear.”

The latest work unveils this mechanism through a series of meticulous experiments showing that cells carrying dormant mutations can turn cancerous when exposed to PM2.5 particles. The pollutant is the equivalent of the ignition spark on a gas hob.

In laboratory studies, Swanton’s team showed that mice that had been engineered to carry mutations in a gene called EGFR, linked to lung cancer, were far more likely to develop cancer when exposed to the pollutant particles. They also revealed that the risk is mediated by an inflammatory protein, called interleukin-1 beta (IL1B), released as part of the body’s immune response to PM2.5 exposure. When the mice were given drugs to block the protein, they were less vulnerable to the pollutants.

The work explains a previous incidental finding in a clinical trial of a heart disease drug, made by Novartis, that people on the drug – an IL1B-inhibitor – had a marked reduction in lung cancer incidence. This could pave the way for a new wave of cancer-preventing medicines, Swanton said.

The team also analysed samples of healthy lung tissue, taken during patient biopsies, and found that the EGFR mutation was found in one in five of the normal lung samples. This suggests that we all carry dormant mutations in our cells that have the potential to turn into cancer – and chronic exposure to air pollution increases the odds of that happening.

“It’s a wake-up call on the impact of pollution on human health,” said Swanton. “You cannot ignore climate health. If you want to address human health, you have to address climate health first.”

How about banning the sales of pure petrol/diesel cars?  Hybrids would cut emissions by 40-50%, plug-in hybrids by 80% and EVs by 100%.  Do we really care about the millions who die from burning fossil fuels, or not?