Severe covid and flu infections may raise the risk of developing lung cancer years later, researchers at the University of Virginia said.
A study conducted in both mice and humans showed that subjects who suffered from severe lung infections were also significantly more likely to die from the disease - the leading cause of cancer deaths in the U.S., with nearly 125,000 deaths expected this year.
There was a 1.24-fold increase in lung cancer cases in people who were previously hospitalized for Covid regardless of whether the patients were smokers or had other health conditions.
The increased risk is tied to changes to lung-protecting immune cells - known as neutrophils and macrophages - that result in a “pro-tumor” environment. The scientists also found significant changes to the epithelial cells that line the lungs and the air sacs that let us breathe.
“These findings have important immediate implications for how we monitor patients after severe respiratory viral infection,” Dr. Jeffrey Sturek, a physician-scientist at the university, explained in a statement.
“We’ve known for a long time that things like smoking increase the risk for lung cancer,” ” he added. “The results from this study suggest that we may need to think about severe respiratory viral infection similarly.”
A study published earlier this year found that Covid vaccines can spark an immune response to fight cancer. Now, the Virginia researchers also the shots provide protective benefits against the changes in the lungs that can lead to lung cancer.
Patients who had only suffered mild Covid infections actually saw a slight decrease in risk of developing lung cancer.
“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 later,” School of Medicine researcher Jie Sun said. “The encouraging news is that vaccination largely prevents those harmful changes for cancer growth in the lung.”
The researchers said they hoped that their findings could help doctors to identify patients who may be at a higher risk of lung cancer after a severe infection.
The scientists also hope the findings can be used to “develop targeted ways to prevent and treat lung cancer after prior pneumonia,” Sun said.
Early and improved treatment can help to reduce the risk of death and potentially even cure some cases of lung cancer.
The researchers recommend considering monitoring patients with routine screening CT scans of the lungs.
Previous studies show that Covid infection could "awaken" dormant cancer cells, and that American adults with a family history of cancer may face a higher risk of developing long Covid.
“Dormant cancer cells are like the embers left in an abandoned campfire, and respiratory viruses are like a strong wind that reignites the flames,” Dr. James DeGregori, of the University of Colorado Anschutz Medical Campus, said in a. statement.
A 2023 study found that colon cancer cells have more of a protein called ACE2, which the COVID-19 virus uses to infect cells.
A separate study published last year found that women who tested positive for Covid were nearly 50 percent more likely to develop metastatic breast cancer tumors in their lungs than women who tested negative and that mice with dormant breast cancer cells that were exposed to Covid or flu saw metastatic tumors appear within two weeks.
However, there is some research showing a benefit of infection and Northwestern Medicine released a study in 2024 showing that Covid infection can transform white blood cells into cancer-fighting cells.
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