Viruses Reawaken Dormant Breast Cancer Cells
New research reveals common infections can trigger metastasis in mice and suggests similar risks for humans.
Common respiratory infections, including COVID-19 and influenza, may reactivate dormant breast cancer cells that have spread to the lungs, potentially leading to new tumor growth. This groundbreaking discovery, made by researchers across multiple institutions, provides the first direct evidence of this concerning link.
Study Uncovers Viral Trigger for Metastasis
Scientists at the University of Colorado Anschutz Medical Campus, Montefiore Einstein Comprehensive Cancer Center (MECCC), and Utrecht University utilized mouse models to investigate the impact of respiratory viruses. They found that infection with SARS-CoV-2 or influenza virus caused dormant cancer cells in the lungs to become active, resulting in rapid metastatic spread and the formation of new lesions.
“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 James DeGregori, Ph.D., senior author and deputy director of the CU Anschutz Cancer Center.
The research identified interleukin-6 (IL-6), a protein released by immune cells during infection, as a key mediator in this process. This finding opens potential avenues for therapeutic intervention, such as using IL-6 inhibitors.
Human Data Supports Viral Link to Cancer Relapse
To validate their findings in human populations, the researchers analyzed two large databases. The UK Biobank data revealed that cancer survivors who contracted COVID-19 faced nearly double the risk of dying from their cancer compared to those who remained negative for the virus. This increased risk was most significant in the first year following infection, mirroring the rapid progression observed in animal models.
Further analysis of the U.S. Flatiron Health database, focusing on female breast cancer patients, indicated that those who contracted COVID-19 were approximately 50% more likely to develop lung metastases than patients who did not have COVID-19. These findings were observed during a follow-up period of about 52 months.
“Our findings suggest that cancer survivors may be at increased risk of metastatic relapse after common respiratory viral infections,” noted Roel Vermeulen, Ph.D., from Utrecht University. “It is important to note that our study focused on the period before COVID-19 vaccines were available.”
Julio Aguirre-Ghiso, Ph.D., co-leader of the study and director of MECCC’s Cancer Dormancy Institute, emphasized the importance of preventative measures. “Our findings indicate that individuals with a history of cancer may benefit from taking precautions against respiratory viruses, such as vaccination when available, and discussing any concerns with their healthcare providers,”
he stated.
The study, published in *Nature*, was also co-led by Mercedes Rincon, Ph.D., with CU Anschutz. Researchers plan to extend their investigations to other cancer types and metastatic sites, recognizing that respiratory infections are a constant factor in daily life.
This research highlights the potential long-term consequences of viral infections for cancer survivors. According to the American Cancer Society, approximately 17.7 million people in the United States were living with a history of cancer in 2023, underscoring the broad public health relevance of these findings (American Cancer Society, 2023).
The study’s reference is: Chia SB, Johnson BJ, Hu J, et al. Respiratory viral infections awaken metastatic breast cancer cells in lungs. Nature. 2025:1-11. doi: 10.1038/s41586-025-09332-0.
