New Research Links Respiratory Infections to Dormant Cancer Cells
Recent studies indicate that respiratory viral infections may reactivate dormant breast cancer cells in mice, but implications for humans remain unclear.
Influenza and SARS-CoV-2 can awaken dormant breast cancer cells in mouse models.
IL-6 is crucial for the initial response of cancer cell reactivation.
Current evidence does not warrant changes in cancer surveillance protocols post-infection.
Recent experimental findings suggest that respiratory viral infections, such as influenza and SARS-CoV-2, may trigger the awakening of dormant breast cancer cells in the lungs of mice. This research highlights a potential link between respiratory illnesses and cancer cell proliferation, although the implications for human health are still uncertain.
The review of emerging studies indicates that disseminated cancer cells can remain inactive in distant tissues for extended periods following treatment. While these cells are viable, various factors, including immune responses and environmental conditions, typically prevent them from forming detectable metastases. The principal study noted that a sublethal infection with influenza A led to a significant increase in the number of cancer cells in mouse lungs shortly after infection.
In this research, it was observed that both influenza A and a mouse-adapted form of SARS-CoV-2 resulted in a marked rise in cancer cell proliferation within two weeks. Notably, the study found no evidence that this increase was due to the spread of cancer cells from primary tumors, suggesting that pre-existing dormant cells had resumed their growth. The cytokine IL-6 was identified as a key mediator in this process, with genetic deficiencies in IL-6 leading to reduced reactivation of cancer cells.
The broader implications of these findings raise concerns about the potential impact of respiratory infections on cancer survivors. Observational studies have shown associations between SARS-CoV-2 infections and negative cancer outcomes, including increased pulmonary metastasis in breast cancer patients. However, these associations do not establish a direct causal relationship, as various factors could influence the outcomes, including treatment interruptions and the severity of the infection.
Despite these findings, experts caution against altering current cancer surveillance practices based solely on respiratory infections. There is no validated biomarker or monitoring strategy that supports changes in imaging or testing protocols following influenza or COVID-19 infections. Further independent studies and human trials are necessary to clarify whether respiratory infections can indeed trigger metastatic relapse in cancer patients.
