Severe COVID or Severe Flu May Raise Risk of Lung Cancer, But Vaccines Helped in Animal Tests
A serious case of COVID-19 or the flu might leave behind more than a lingering cough or fatigue. New research suggests these infections could reshape the lungs in ways that make cancer more likely in the months — or even years — after infection.
Published in Cell, the findings reveal that severe viral infections can alter the lung’s immune environment, creating conditions where tumors are more likely to grow. But there is a bright side, as vaccination appears to prevent many of these harmful changes.
Scientists say their findings could have major implications for the millions of people worldwide who have recovered from severe respiratory illnesses in recent years.
“A bad case of COVID or flu can leave the lungs in a long-lasting ‘inflamed’ state that makes it easier for cancer to take hold. The encouraging news is that vaccination largely prevents those harmful changes for cancer growth in the lung,” said Jie Sun, a researcher from the University of Virginia School of Medicine, in a press release.
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How Respiratory Illness Connects to Lung Cancer
To investigate the surprising connection between respiratory illness and lung cancer, researchers studied both laboratory mice and human patient data. Mice with severe lung infections were significantly more likely to develop lung cancer later and were also more likely to die from it.
When the team analyzed clinical data from people, the same patterns appeared. Patients who had previously been hospitalized with COVID-19 showed a higher incidence of lung cancer compared with those who had not experienced severe infection.
“These findings have important immediate implications for how we monitor patients after severe respiratory viral infection,” explained Jeffrey Sturek, a collaborator on the project. “We’ve known for a long time that things like smoking increase the risk of lung cancer. The results from this study suggest that we may need to think about severe respiratory viral infection similarly.”
Mice studies also helped the team uncover a possible biological explanation for their results. Severe infections dramatically altered immune cells in the lungs, particularly neutrophils and macrophages, which normally help defend the body from pathogens. After infection, some of these cells began behaving differently, producing signals that created a chronically inflamed, tumor-friendly environment where cancer cells could thrive.
Vaccines as Unexpected Cancer Protection
One of the most hopeful discoveries from the study involves vaccines.
In animal experiments, prior vaccination prevented the lung changes that appeared to promote cancer growth. Because vaccines train the immune system to fight infections quickly and effectively, they often reduce the severity of illness. In this case, that reduced severity may also protect lung tissue from long-term immune disruptions.
“With tens of millions of people globally experiencing long-term pulmonary [COVID-19] sequelae, these findings carry significant implications for clinical care. Individuals recovering from severe viral pneumonia, particularly those with smoking history, may benefit from enhanced lung cancer surveillance, and preventing severe infection through vaccination may confer indirect cancer protection benefits,” said the study authors.
How This Impacts the Future of Lung Cancer Research
Overall, the research team hopes their findings will help doctors identify patients who may need closer monitoring after severe respiratory illness. Detecting lung cancer early dramatically improves treatment outcomes, making surveillance especially important for high-risk groups.
“Our goal is to help doctors identify who may be at higher risk of lung cancer after a severe infection, and develop targeted ways to prevent and treat lung cancer after prior pneumonia. We also believe that vaccines don’t just prevent acute hospitalization after contracting the virus. They may also reduce the long-term fallout of severe infection, including the kind of immune scarring that can increase cancer risk,” concluded Sun.
This article is not offering medical advice and should be used for informational purposes only.
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