New Delhi: A new study has revealed that common respiratory infections, including Covid-19 and influenza, may reactivate dormant breast cancer cells in the lungs, potentially leading to new metastatic tumours. The findings could have important implications for cancer survivors, especially those in remission.
Published in the prestigious journal Nature, the research was conducted by scientists from the Albert Einstein College of Medicine in the US and Utrecht University in the Netherlands. It is based on experiments in mice and a meta-analysis of data from human cancer patients.
Dr. Julio Aguirre-Ghiso, the lead author from Einstein, explained that their results support earlier evidence suggesting that inflammation caused by infections may "wake up" cancer cells that had previously spread and become dormant in distant organs, such as the lungs. These are known as disseminated cancer cells (DCCs), which can remain inactive for years before reactivating and forming new tumours.
To explore this connection, the researchers exposed mice with dormant breast cancer cells to either SARS-CoV-2 (the virus responsible for COVID-19) or influenza. Both viruses triggered the reactivation of these dormant cells. Within just a few days, the mice showed a rapid increase in metastatic cells, and visible lung tumours developed within two weeks.
Molecular analysis identified interleukin-6 (IL-6)—an immune protein released during infections—as the key driver of this reactivation. The researchers suggested that drugs targeting IL-6 or other inflammatory pathways could help prevent cancer from returning after viral infections.
To examine the relevance to humans, the team analysed two large patient databases. They found that cancer patients who had recovered and later contracted respiratory infections were at higher risk of cancer recurrence, especially within the first year after infection.
Dr. Roel Vermeulen from Utrecht University emphasised that these findings relate to the pre-vaccine era. However, they emphasise the importance of cancer survivors taking precautions against respiratory viruses, including vaccinations and regular consultations with healthcare providers.