Respiratory Infections May Reactivate Dormant Breast Cancer Cells

A groundbreaking study published in Nature reveals that common respiratory infections, such as COVID-19 and influenza, may awaken dormant breast cancer cells in the lungs, increasing the risk of metastasis. Researchers from the University of Colorado Cancer Center and the Montefiore Einstein Comprehensive Cancer Center conducted experiments using a mouse model and observational data from human cohorts to explore this phenomenon. In the study, mice infected with SARS-CoV-2 or influenza experienced a dramatic increase in the activation of dormant disseminated cancer cells (DCCs) in the lungs. This reactivation led to a 100- to 1,000-fold increase in cancer cell burden. Observational data from human studies corroborated these findings, showing a higher risk of death and metastatic lung disease among cancer survivors infected with COVID-19. Specifically, cancer survivors who tested positive for COVID-19 had an almost two-fold higher risk of cancer-related death compared to those who remained uninfected. Among women with breast cancer, the risk of developing metastatic disease in the lungs increased by 44%. The study identified interleukin-6 (IL-6), an inflammatory protein released during infections, as a key driver of this reactivation process. Once awakened, these cancer cells are protected by the immune system, making them resistant to elimination. While the findings highlight the potential risks of respiratory infections for cancer survivors, researchers emphasize the importance of precautionary measures, such as vaccination and discussions with healthcare providers. Further research is needed to fully understand the mechanisms and implications of this phenomenon.

Published: 7/30/2025