Respiratory Infections and Lung Cancer Risk: What the Latest Research Reveals

Modern research suggests a concerning link between severe respiratory infections, like COVID-19 and influenza, and an increased risk of developing lung cancer months or even years later. This finding highlights the long-term consequences of respiratory viruses, extending beyond the initial infection itself.

How Respiratory Viral Infections May Increase Lung Cancer Risk

Researchers investigated the potential impact of lung injury from respiratory illnesses on long-term cancer risk by examining data from both animal models and human populations. Studies on mice demonstrated that those experiencing severe lung infections from influenza or COVID-19 were more likely to develop lung cancer and succumb to the disease.

To determine if similar effects occur in humans, researchers analyzed health data from over 76 million adults across the United States, Lebanon, and Saudi Arabia who were hospitalized with COVID-19 before 2022 and had no prior cancer diagnoses. The study tracked these individuals for new cancer diagnoses following their hospitalization.

The findings revealed that individuals hospitalized with COVID-19 had a 24% increased risk of receiving a lung cancer diagnosis, regardless of their smoking history or other health conditions. According to study author Jie Sun, PhD, a professor of medicine and the codirector of the Beirne B. Carter Center for Immunology Research at the University of Virginia School of Medicine, “That is considered a pretty significant increase in lung cancer, particularly considering the relatively short time window.”

The Role of Inflammation

James DeGregori, PhD, a professor of biochemistry and molecular genetics at the University of Colorado Anschutz School of Medicine and the interim director of the University of Colorado Cancer Center, explains that severe viral infections trigger changes in immune system cells that normally protect lung tissue. This resulting chronic inflammation may create an environment more susceptible to cancer development. “The findings basically show a ‘memory’ function within the lung environment. So the environment of the lung seems to be switched because of this infection, and that switch within the lung is more conducive to cancer initiation or progression,” he says.

It’s important to note that other viral infections are already known to contribute to cancer development, such as hepatitis B (linked to liver cancer) and human papillomavirus (HPV) (linked to cervical cancer).

Study Limitations and Considerations

While this study establishes a link between prior viral infection and lung cancer development, it’s essential to acknowledge its limitations. Researchers point out that participants hospitalized or diagnosed with COVID-19 before January 2022 likely underwent medical imaging and follow-up care, potentially influencing the results. This increased the likelihood of incidental findings and the detection of pre-existing, undiagnosed lung conditions.

the study did not account for patients’ COVID-19 vaccination status, a factor that could play a role in disease severity and subsequent cancer risk. As Wafik S. El-Deiry, MD, PhD, the director of the Legorreta Cancer Center at Brown University, notes, understanding the impact of vaccination is crucial for a more complete picture.

However, data from animal studies clarify that the virus itself isn’t necessarily the sole culprit, as other viral infections causing severe pneumonia in mice also demonstrated an increased risk of lung cancer.

Protecting Yourself and Reducing Risk

Researchers emphasize the importance of vaccination as a protective measure against severe viral infections and potential long-term cancer risks. They also recommend that healthcare providers consider close monitoring for lung cancer screening in individuals with a history of severe COVID-19, flu, or pneumonia.

“Severe viral infections are not only harmful in the acute phase, but may also contribute to the development of chronic diseases, including cancer. It is important to protect ourselves from severe infections whenever possible,” says Dr. Sun.

Individuals at high risk of severe illness should discuss preventative medications, such as Tamiflu (for flu) or Paxlovid (for COVID-19), with their healthcare team to prevent mild infections from progressing to more serious conditions.