Planes, space & GLP-1's…
This week, Professor Stebbing highlights the cancer risks of cosmic radiation for airline crews, cancer-drug research in space, and emerging links between GLP-1 drugs, ageing and cancer.
Radiation Exposure and Cancer Risk in Aviation Workers
A major new study published in JAMA Internal Medicine has found that, out of more than 500 occupations examined across 12.7 million deaths, flight attendants and pilots have the highest proportion of deaths from cancers linked to radiation exposure. Around 6.9% of flight attendant deaths were from radiation-associated cancers (roughly one in fourteen), compared with 6.7% for pilots and approximately 5% for the general working population.
Researchers believe the primary cause is cosmic radiation. At altitude, the atmosphere is thinner and offers less protection from the high-energy particles streaming in from space. Air crew are estimated to absorb more radiation, on average, than workers in any other job. The types of cancers most elevated among aircrew included breast cancer, prostate cancer, melanoma, and cancers of the central nervous system, with pilots also showing higher rates of leukaemia.
The findings have real-world legal weight too: a French court recently recognised the breast cancer of a former Air France flight attendant, who had logged more than 12,600 flying hours over 30 years, as an occupational disease, a landmark ruling in Europe. The study also touches on a related chapter in radiation history: Chernobyl. The 1986 nuclear disaster caused 28 confirmed deaths from acute radiation sickness and, in the years that followed, more than 6,000 cases of thyroid cancer were diagnosed in children and adolescents who were exposed to radioactive iodine. The vast majority survived; fewer than 15 died. Crucially, large population studies have not found major increases in overall cancer rates among the broader Chernobyl-exposed public, contrary to some earlier fears.
The World Health Organisation has estimated that up to around 4,000 additional cancer deaths may eventually occur as a statistical consequence among the 600,000 most heavily exposed individuals, a serious toll, but far smaller than some projections in the immediate aftermath of the disaster.
Read more: Harvard Medical School news summary | CNN report
Manufacturing Cancer Drugs in Space
One of the more unexpected frontiers in cancer research involves sending drugs (and cancer cells themselves) to the International Space Station to see what happens when gravity is taken out of the equation.
Researchers at Merck found that pembrolizumab (Keytruda), a widely-used cancer immunotherapy that works by releasing the brakes on the immune system, forms smaller and more uniform crystals in microgravity. On Earth, the drug must be given as a lengthy intravenous infusion, partly because of the way it behaves as a liquid. The more uniform crystals produced in space hinted at the possibility of a subcutaneous injection instead: faster, simpler, and far more convenient for patients.
Merck ultimately developed an injectable version through Earth-based manufacturing, but the space experiments had shown that microgravity could reveal new possibilities for drug formulation. More directly relevant to cancer biology, researchers at UC San Diego sent breast cancer cells to the Space Station to test an experimental cancer drug in conditions where gravity is effectively absent.
Cancer cells in microgravity tend to cluster into three-dimensional structures that more closely resemble how tumours actually behave in the body, and they appear to respond to treatments faster. Biological changes that would take weeks or months to observe on Earth were visible within days in space, with microgravity acting as a kind of biological fast-forward button. Organoids (small lab-grown tissue models used to study cancer) also grow more uniformly and survive better in microgravity, which could make them more useful as research tools.
None of this means cancer drugs will be manufactured in space at scale any time soon, but it illustrates how changing the physical environment of cells can unlock new insights into how diseases behave and how drugs might be improved.
Read more: ISS National Lab: Merck space station research improves cancer drug delivery | Published research: pembrolizumab microgravity crystallisation (npj Microgravity)
GLP-1 Drugs, Ageing, and the Broader Cancer Picture
You may have heard of Ozempic or Wegovy, the injectable drugs originally developed for type 2 diabetes and weight loss that have become household names. Their active ingredient, semaglutide, works by mimicking a hormone called GLP-1 that helps regulate blood sugar, appetite, and metabolism. A striking new study published this month in Nature suggests semaglutide may do something even more fundamental: slow the process of ageing itself.
In the study, older female mice given semaglutide lived around 12% longer on average than untreated mice: a median of 834 days compared with 742 days in the control group. But lifespan was only part of the story. The treated mice also performed better on tests of balance, memory, and physical endurance; they had better blood sugar control; and gene expression analysis showed that several hallmarks of ageing, including chronic inflammation and reduced regenerative capacity, were measurably reduced. Importantly, these benefits appeared to go beyond simply eating less (semaglutide-treated mice ate about 24% less food), suggesting the drug works through additional biological pathways.
Why does this matter for cancer? Cancer is fundamentally a disease of ageing: the vast majority of cancers become more common as we grow older, driven by accumulated DNA damage, chronic inflammation, and the gradual breakdown of the body's quality-control systems. Prof Justin Stebbing, along with colleagues, has written a commentary in the British Journal of Clinical Pharmacology setting out what they call the Blueprint Theory of Aging.
The central idea is that ageing and the cluster of diseases that come with it, including cancer, heart disease, type 2 diabetes, and neurodegeneration, are not entirely separate conditions but overlapping consequences of shared biological processes going wrong. When normal pathways that serve useful purposes in youth become dysregulated as we age, they can drive disease across multiple organ systems simultaneously. Seen through this lens, the widening list of conditions that GLP-1 drugs appear to help with, from heart disease and kidney disease to possible effects on brain health, begins to make more sense.
By targeting shared upstream processes like chronic inflammation, insulin resistance, and metabolic dysfunction, these drugs may be addressing a common root rather than separate diseases. Cancer sits within that cluster. While semaglutide is not a cancer treatment, the research raises the intriguing possibility that drugs targeting the biology of ageing may, in time, have a role to play in cancer prevention alongside their more established benefits. Read more: Nature study: semaglutide extends lifespan in mice | NIH news release | Blueprint Theory of Aging, British Journal of Clinical Pharmacology
As always, if anything in this week's update feels relevant to your own situation or that of someone you care for, please speak with your clinical team before making any decisions. Research findings, even encouraging ones, take time to translate into treatment guidelines.
With thanks to Professor Justin Stebbing for his insights and research.