A new study published in Nature reveals that common respiratory viruses, including SARS-CoV-2 and influenza, can “wake up” dormant breast cancer cells that have migrated to the lungs, potentially triggering the rapid development of metastatic tumours. The research, which combined mouse experiments with a meta-analysis of human patient data, provides compelling evidence for the role of inflammation in cancer relapse.
Researchers at the Albert Einstein College of Medicine first demonstrated in mice that infection with either virus led to a surge in interleukin-6 (IL-6) levels—a pro-inflammatory molecule released during immune responses. Within days of infection, previously inactive disseminated cancer cells (DCCs) in the lungs began proliferating en masse, and visible metastatic lesions appeared within two weeks. Blocking IL-6 in the animal models significantly blunted this resurgence, suggesting that targeted immunotherapies could help prevent post-infection relapses.
To explore human relevance, investigators analysed two large healthcare databases tracking cancer survivors. They found a marked increase in metastatic relapses among breast cancer patients who experienced respiratory infections, particularly within the first year after falling ill. “The rapid progression mirrors what we observed in animals,” noted Roel Vermeulen of Utrecht University, a co-author on the study.
Lead author Julio Aguirre-Ghiso emphasized the clinical implications: “Individuals with a history of cancer may benefit from taking precautions against respiratory viruses, such as vaccination when available, and discussing any concerns with health care providers.” The team cautioned that their human data predated widespread COVID-19 vaccination, and further research is needed to assess how vaccines or antiviral treatments might modify this risk.
Overall, this work underscores inflammation—specifically IL-6 signaling—as a critical trigger in the transition from dormancy to active metastasis. It paves the way for prospective trials testing whether IL-6 inhibitors or other immunomodulators can keep dormant cancer cells in check following respiratory infections.
