Research suggests a potential link between severe viral infections, such as COVID-19 or influenza, and the reactivation of dormant cancer cells. According to data published in Nature and analyses of U.K. Biobank records, patients with a history of cancer who contracted COVID-19 showed an increased risk of recurrence, potentially driven by immune-system inflammation rather than the virus acting as a direct carcinogen.
How can a virus trigger cancer recurrence?
Viral infections may act as “fuel for the fire” for dormant cancer cells, according to James DeGregori, a researcher at the University of Colorado Anschutz lab. When the body fights a severe infection, the immune system releases cytokines—proteins meant to coordinate defense. In some instances, this leads to a “cytokine storm,” characterized by an excess of proteins like interleukin-6 (IL-6).
DeGregori’s team observed that dormant breast cancer cells in mice reactivated in response to these high IL-6 levels. While this biological process remains to be definitively proven in humans, the correlation observed in healthcare databases suggests that the inflammatory response to a virus, rather than the virus itself, may be the primary mechanism behind recurrence.
Unlike viruses such as human papillomavirus (HPV) or hepatitis B and C, COVID-19 is not considered an oncogenic (cancer-causing) virus. Its structural properties are fundamentally different, meaning it does not typically initiate cancer in healthy cells.
What is the role of mitochondrial dysfunction?
Some researchers offer an alternative explanation for how infections might influence cancer growth. Dr. Doug Wallace, director of the Center for Mitochondrial and Epigenomic Medicine at the Children’s Hospital of Philadelphia, points to the role of mitochondria—the energy-producing centers of a cell.
Wallace suggests that high levels of IL-6 may inhibit mitochondrial function. Because SARS-CoV-2 is particularly effective at shutting down these cellular powerhouses, this dysfunction could simultaneously contribute to the lingering effects of long COVID and create an environment that encourages dormant cancer cells to reawaken. This hypothesis contrasts with the cytokine-focused model by placing the emphasis on cellular metabolic failure rather than just chemical signaling.
Why is this data emerging now?
The global scale of the COVID-19 pandemic provided a unique, albeit unfortunate, dataset for researchers. Dr. Stanley Perlman, a microbiologist at the University of Iowa, notes that the sheer number of infections created a “denominator of 7 billion people,” allowing scientists to identify patterns that would be impossible to track with rarer illnesses.
Previously, it was difficult to study the impact of viruses like influenza on cancer because most cases were treated at home and never appeared in medical records. The rigorous data collection during the pandemic has allowed researchers like Dr. Aditya Bardia at the UCLA Health Jonsson Comprehensive Cancer Center to begin documenting these associations, though he notes that many findings, including his own, are still awaiting peer review.
For patients with a history of cancer or other chronic conditions, experts like Dr. Patrick Moore of the University of Pittsburgh emphasize the importance of staying current with vaccines for respiratory syncytial virus (RSV), influenza, and COVID-19 to avoid the systemic stress of a severe infection.
Common Questions About Viral Infection and Cancer Risk
Is COVID-19 considered a cancer-causing virus?
No. According to researchers at the University of Pittsburgh and other institutions, there is no sufficient evidence to classify COVID-19 as an oncogenic virus. It does not possess the structural characteristics of known cancer-causing viruses like HPV.
Should cancer survivors be more concerned about COVID-19?
Medical experts suggest that cancer survivors should treat viral infections with caution. Dr. Eric Winer of the Yale Cancer Center notes that while the evidence is interesting, it remains in the early stages. The primary recommendation is to continue taking reasonable precautions to avoid severe respiratory infections.
Does this mean cancer recurrence is inevitable after an infection?
No. The research describes an association, not a certainty. Most researchers, including Dr. Winer, stress that while the theory is compelling, there is no definitive causal link established yet. Further study is required to understand the specific risks for different patient populations.
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