Flu and COVID Might “Reignite” Dormant Cancer Cells, Study Says

A new study is raising eyebrows — and concerns — by suggesting that viruses like the flu and COVID-19 might actually “wake up” dormant cancer cells in people with a history of the disease.

Yep, you read that right.

Researchers at the University of Colorado Cancer Center and Montefiore Einstein’s dormancy institute tested the idea on mice carrying disseminated cancer cells — basically, cancer cells that had broken away from a primary tumor and were just… chilling in other parts of the body, like the lungs. These cells were in a dormant state, meaning they weren’t growing or spreading — until the mice were exposed to respiratory viruses like SARS-CoV-2 (COVID) or the flu.

Once infected, the inflammation triggered by the virus appeared to “reawaken” those sleepy cancer cells. The researchers likened it to embers in a campfire suddenly roaring back to life when the wind picks up.

“Dormant cancer cells are like the embers left in an abandoned campfire, and respiratory viruses are like a strong wind that reignites the flames,” said senior author James DeGregori.

Within days of infection, the mice showed signs of cancer cells multiplying again, and within two weeks, they had full-blown metastatic lesions in the lungs. The response was linked to interleukin-6, a protein involved in inflammation.

But — before the panic sets in — there’s a catch.

Co-lead researcher Julio Aguirre-Ghiso noted that once the infections cleared, the cancer cells often returned to their dormant state. That means a single virus exposure might not be enough to cause full-blown metastasis — multiple “reawakening” events might be needed.

He also emphasized that this is still early research — step one, really — and more studies are needed, especially in humans. But interestingly, the findings do align with earlier human data, including research showing that unvaccinated cancer patients who got COVID were twice as likely to die from cancer complications.

So what does this mean?

• If you’re a cancer survivor, this is one more reason to take respiratory viruses seriously.
• It could also open the door to new strategies in cancer treatment, like targeting inflammation or bolstering immune responses to prevent metastasis.

For now, researchers hope the study sparks (pun intended) more investigation into how infections interact with cancer, and how we might use that knowledge to predict or prevent relapses.

Nature and USA Today contributed to this report.