A severe case of COVID-19 or influenza may quietly increase your risk of developing lung cancer years later, according to new research from UVA Health. Scientists discovered that serious viral infections can alter immune cells in the lungs, leaving behind chronic inflammation that may help tumors develop months or even years after recovery. The encouraging news: vaccination appears to prevent many of these dangerous lung changes. How Does a Severe Respiratory Infection Increase Cancer Risk? Researchers led by Jie Sun, PhD, at UVA's Beirne B. Carter Center for Immunology Research studied how severe respiratory infections affect the lungs long-term. The findings were striking. In laboratory mice, those that experienced severe lung infections were significantly more likely to develop lung cancer later and were also more likely to die from the disease. When the team analyzed patient data, they found a similar pattern. People who had been hospitalized with COVID-19 showed a higher rate of lung cancer diagnoses compared to those with milder infections. The analysis revealed a 1.24-fold increase in lung cancer incidence, meaning patients had roughly 24% higher odds of developing lung cancer after severe COVID-19 hospitalization. "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," explained Jie Sun, co-director of UVA's Carter Center and a member of UVA's Division of Infectious Diseases and International Health. "The encouraging news is that vaccination largely prevents those harmful changes for cancer growth in the lung". What Changes Happen Inside Your Lungs After Severe Infection? The research uncovered the biological mechanisms behind this increased cancer risk. Experiments in mice revealed major changes in immune cells called neutrophils and macrophages, which normally help defend the lungs. After severe infection, some neutrophils began behaving abnormally and contributed to a persistent inflammatory environment described as "pro-tumor," meaning it actively supports cancer growth. The scientists also found significant changes in epithelial cells that line the lungs and the tiny air sacs responsible for breathing. These alterations create an environment where cancer cells can more easily take hold and progress. Importantly, this elevated risk was seen regardless of whether individuals smoked or had other medical conditions, suggesting that the infection itself poses an independent cancer risk factor. Ways to Protect Yourself After Severe Respiratory Infection - Get Vaccinated: Prior vaccination appeared to block many of the lung changes linked to cancer development. Vaccines help the immune system respond more effectively to infections, which reduces how severe the illness becomes and prevents the harmful immune changes that increase cancer risk. - Seek Enhanced Lung Monitoring: If you've recovered from severe COVID-19, flu, or pneumonia, especially with a smoking history, ask your doctor about enhanced lung cancer surveillance. This may include routine screening CT scans of the lungs to catch cancer early when treatment is most effective. - Report Persistent Symptoms: Pay attention to any lingering respiratory symptoms or changes in your health after severe infection. Early detection of lung cancer significantly improves treatment outcomes and survival rates. Who Should Be Most Concerned About This Risk? The study identified specific groups who may benefit from closer monitoring. Patients who were hospitalized with COVID-19 showed the elevated cancer risk. However, individuals who experienced only mild infections did not show this increased risk and actually had a slight decrease in lung cancer incidence. Jeffrey Sturek, MD, PhD, a UVA physician-scientist who collaborated on the study, noted the clinical implications: "We've known for a long time that things like smoking increase the risk for lung cancer. The results from this study suggest that we may need to think about severe respiratory viral infection similarly. For example, in some patients who are at high risk for lung cancer based on smoking history, we recommend close monitoring with routine screening CT scans of the lungs to catch cancer early. In future studies, we may want to consider a similar approach after severe respiratory viral infection". The research team emphasized that with tens of millions of people globally experiencing long-term pulmonary complications from COVID-19, 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. What Role Does Vaccination Play in Prevention? One of the most encouraging findings from this research is that vaccination may offer protection beyond preventing acute illness. Prior vaccination appeared to block many of the lung changes linked to cancer development. This suggests that vaccines don't just prevent hospitalization from the virus itself; they may also reduce the long-term fallout of severe infection, including the kind of immune scarring that can increase cancer risk. The study was published in the journal Cell and involved a comprehensive research team from UVA's Paul and Diane Manning Institute of Biotechnology. The findings suggest that staying up-to-date with flu and COVID-19 vaccines may provide indirect cancer protection benefits by preventing the severe infections that trigger these harmful immune changes.
