Cancer survivors who caught COVID-19 were at higher risk of deadly relapses, data from almost 5,000 UK Biobank participants revealed.
Summary
Respiratory viruses can wake ‘sleeping’ breast cancer cells in the lungs and cause them to grow into tumours. The discovery could lead to treatments that suppress this reactivation process, which can lead to deadly relapses years or even decades after the initial cancer diagnosis.
Dormant cancer cells are like the embers left in an abandoned campfire, and respiratory viruses are like a strong wind that reignites the flames.
Professor James DeGregori, University of Colorado, US
COVID-19 and flu can reactivate ‘sleeping’ tumour cells that have spread to the lungs. “Dormant cancer cells are like the embers left in an abandoned campfire, and respiratory viruses are like a strong wind that reignites the flames,” explained study co-leader James DeGregori from the University of Colorado, US.
This could explain why cancer death rates increased early during the COVID-19 pandemic – something that isn’t fully explained by delays in treatment and screening during that time. The discovery could lead to treatments that suppress the reactivation process.
Inflammation reignites cancer
People who are in remission from breast cancer often have dormant cancer cells in various parts of their body, including the lungs. These sleeper cells can reactivate and trigger deadly relapses, years or even decades after the initial cancer diagnosis.
Chronic infections, for example with the hepatitis C virus, are known to cause cancer. “What is new and interesting here is that acute respiratory infections can lead to the development of metastases due to the inflammatory response they cause,” immunology specialist Carsten Watzl from the Leibniz Research Centre for Working Environment and Human Factors in Germany told the Science Media Centre.
De Gregori’s team found that dormant cancer cells in the lungs of mice started multiplying again after the animals had been infected with a COVID-19 or flu virus. Within two weeks, these cells had grown into tumours.
Higher risk of deadly relapses
Data from more than 40,000 cancer survivors, including nearly 5,000 UK Biobank participants, also showed that cancer survivors who had COVID-19 were nearly 1.5 times more likely to experience deadly relapses as those who never tested positive for COVID-19. “The effect was most pronounced in the first year after infection,” said study co-leader Roel Vermeulen from Utrecht University in the Netherlands.
Vaccination significantly reduces the risk of severe disease and thus of a severe inflammatory response after influenza or SARS-CoV-2 infection.
Professor Dr Carsten Watzl, Leibniz Research Centre for Working Environment and Human Factors, Germany
The data was collected at the beginning of the pandemic, when no vaccines were available. “Vaccination significantly reduces the risk of severe disease and thus of a severe inflammatory response after influenza or SARS-CoV-2 infection,” Watzl explained. “It would therefore be expected that vaccination could also reduce the effect on metastasis formation.”
In their mouse experiments, the team revealed several immune components that drive the cancer reactivation and that could be targeted with medications. “We are actively working to develop such interventions,” DeGregori told Newsweek.
Related publication
- Nature paper, July 2025
