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.
The findings, published in Nature on 30 July1, seem to extend to humans too: data from thousands of people show that infection with the coronavirus SARS-CoV-2 is linked with a nearly twofold increase in cancer-related death, possibly helping to explain why cancer death rates increased early during the COVID-19 pandemic.
The results are “really quite dramatic”, says James DeGregori, a cancer biologist at the University of Colorado School of Medicine in Aurora, and an author of the study. “Respiratory-virus infections didn’t just awaken the cells,” he says: they also caused them to proliferate, or multiply, “to enormous numbers”.