Hidden in the lungs of some breast cancer survivors are tumour cells that can remain dormant for decades — until they one day trigger a relapse. Now, experiments in mice show that these rogue cells can be roused from their slumber by common respiratory illnesses such as COVID-19 or the flu.

Mice with a handful of cancerous cells in their lungs experienced a 100-fold increase to this number after being infected with swine flu

Respiratory illnesses such as Covid and the flu can awaken dormant cancer cells in the body and cause them to spread, scientists have warned. Researchers found when mice were exposed to Covid or influenza, dormant cancer cells woke up and spread rapidly.