Respiratory viruses can awaken dormant breast cancer cells

Scientists from the University of Colorado, Montefiore Einstein Cancer Center, and Utrecht University have presented the first direct evidence that common respiratory infections—such as influenza and COVID-19—can “awaken” dormant breast cancer cells that have already spread to the lungs, thereby creating conditions for the development of new metastases. The findings, published in the journal Nature, were obtained in experiments on mice and confirmed by clinical data showing increased mortality and frequency of lung metastases in cancer survivors infected with SARS-CoV-2.

Before the study, there were already assumptions that inflammatory processes could awaken disseminated cancer cells (DCCs) — cells that have separated from the primary tumor and spread to other organs, where they can remain dormant for a long time. To test this hypothesis, the team used unique models of metastatic breast cancer in mice. These models include dormant cancer cells in the lungs and reproduce one of the key features of the disease in humans.

The scientists infected mice with SARS-CoV-2 or influenza and found that in both cases, respiratory infections led to the activation of dormant disseminated cancer cells (DCCs) in the lungs. Within a few days of infection, there was a rapid growth of metastatic cells, and after two weeks, full-fledged metastatic foci had formed.

Molecular analysis revealed that DCC activation is triggered by interleukin-6 (IL-6), a protein produced by the immune system in response to infection or injury. This discovery suggests that IL-6 blockers or other immunotherapeutic drugs targeting this pathway may help prevent or reduce the risk of recurrent metastasis after a viral infection.

One source of data is the UK Biobank, which contains information on more than 500,000 people who were diagnosed with cancer and other diseases before the pandemic began. Researchers from Utrecht University and Imperial College London investigated whether COVID-19 was associated with increased cancer mortality among patients with a history of cancer. Particular attention was paid to people who had been diagnosed with cancer at least five years before the pandemic, indicating probable remission. The sample included 487 people who tested positive for COVID-19, and they were compared with a control group of 4,350 people who tested negative.

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Published: 16.08.2025

Updated: 15.08.2025

Medical author, Medical editor:

Stepan Yuk

Medical expert:

PhD. Olexandr Voznyak