COVID-19 and Cancer: New Data Raises Concern, but Scientists Say More Research Is Needed

A report by Los Angeles Times journalist Corinne Purtill highlights a troubling scientific question: could viral infections such as COVID-19 — and possibly influenza — play a role in reactivating dormant cancer cells in some patients?

The concern began with research at the University of Colorado Anschutz, where scientists observed something unusual in laboratory mice. When mice carrying dormant breast cancer cells were infected with either influenza or SARS-CoV-2, they were significantly more likely to develop aggressive lung tumors.

Researchers then looked at human health databases and found patterns that appeared similar. According to the report, cancer survivors in the U.K. Biobank who contracted COVID-19 in 2020 — before vaccines were available — were more likely to die from recurring cancer, especially within the year after infection.

A separate U.S. breast cancer database also found that patients in remission who got COVID were more likely to later develop metastatic lung tumors than patients who did not contract the virus.

⚠️ Important: This does NOT mean COVID-19 causes cancer.
Scientists are not saying that. What they are studying is whether a strong viral infection can trigger inflammation powerful enough to “wake up” cancer cells that were already present in the body but had been kept under control by the immune system.

One possible factor is interleukin-6, a protein linked to inflammation. In severe COVID cases, the immune system can overreact, creating what is known as a cytokine storm. That intense inflammatory response may create conditions that allow dormant cancer cells to grow again.

Researchers also acknowledge that part of the rise in advanced cancers during the pandemic was likely caused by delayed screenings, missed appointments and postponed treatments. But some scientists believe that delayed care may not explain everything.

The larger message is clear: COVID-19 should not be seen only as a respiratory virus. The pandemic created a massive amount of data that is now helping researchers understand how viral infections may affect the body long after the initial illness has passed.

📌 Bottom line:
There is no reason to panic, but there is every reason to take prevention, vaccination, medical checkups and cancer follow-ups seriously — especially for people with a history of cancer or weakened immune systems.

Science is still investigating, but one lesson is already clear: viral infections can have deeper and longer-lasting effects than many people imagined.