An important study, published in August 2025 in the prestigious Jama medical journal, brings to light new data, which can change the way in which the infections on survivors of cancer are perceived.

The Professor of Therapeutic-Epidemiology-Political Medicine, Pathologist (Nursing School of Medicine, EKPA School of Medicine, Alexandra Hospital) Theodora Psaltopoulou, Biologist Alexandra Stavropoulou, Dr. Maria Kaparelou (Pathologist-Oncologist) and Thanos Dimopoulos (T. Rector of EKPA, Professor of Therapeutic-Oncology-Hematology, Director of the Therapeutic Clinic of the School of Medicine, Alexandra Hospital) reports that in the first year of the first year, to be recorded by colleagues reports of unusually increased incidents of people who have been displayed suddenly metastatic cancermainly breast and intestine.

The prevailing explanation attributed the phenomenon to the delays of medical examinations and treatments due to the pandemic, which resulted in diagnoses being made in more advanced stages. However, as he pointed out, “cancers do not evolve like that, they do not pass a small bump at a terminal within three months.”

This led him to investigate a different case: could respiratory viruses, such as influenza and Covid -9, “wake up” to “wake up” in inactive cancer cells and cause metastasis?

The investigation

A study, recently published in Nature magazine, began with experiments in mice that were genetically planned to bring inactive cancer cells. These cells came from the breast and were installed in the lungs and other organs.

Normally, these cells remain inactive for about a year before they begin to grow and cause cancerous damage. However, when mice were exposed to a mild dose of influenza virus, the researchers noticed that within a few days the cells were activated and multiplied. Within two weeks they had evolved into metastatic tumors.

The same thing happened when mice were infected with a SARS-COV-2 mice adapted: Within 28 days there was a “impressive increase” of cancer cells.

“Viral infection significantly accelerates the growth of these cells“, Said John Alcorn, Professor of Pediatrics at the University of Pittsburgh.

To look at whether the same thing happens to humans, the researchers analyzed data from two large bases. In the first, the UK Biobank, which included more than 4,800 recession cancer patients, found that those who had a positive Covid-19 test in 2020 had almost twice the risk of cancer death compared to those who had a negative test. The correlation was stronger in the first months after the infection. At the second base, Flatiron Health, which contained data of about 37,000 women in breast cancer recession, those who had been involved in Covid-19s showed an increased chance of developing metastases to the lungs, confirming the findings of mice experiments.

OR Influenza and Covid -9 cause intense inflammation in the bodyas the immune system tries to fight the virus. The researchers focused on a particular protein, interleukin-6 (IL-6), which is temporarily increased during an infection. IL-6 plays a crucial role in the body’s defense, but when there is a presence of cancer cells it can enhance their growth.

In mice, the Il-6 It seemed to be a key factor in awakening cancer cells. However, even when its levels returned to normal 15 days after the infection, the cells continued to grow, indicating that there are secondary mechanisms. One of them appears to be about T-cells: CD4 T-cells suppress the action of CD8 T-cells, which are responsible for the extermination of cancer cells. Thus, an environment is created that allows cancer to spread uncontrollably.

Although the data indicate a connection between viral infections and metastases, there are still many questions. Researchers want to consider whether the same applies to other viruses, as well as other types of cancer, as well as for different organs, such as the liver, where they are often installed with latent cancer cells.

Until there are answers, experts emphasize the value of prevention. Vaccination against influenza and Covid-19 does not eliminate the risk, but significantly reduces the chances of severe infection.

Professor Montgomery emphasizes that attention should not be turned into fear that restricts the lives of cancer survivors. After all, how careful everyone is to be a personal choice.

This study sheds light on a new, alarming mechanism: respiratory infections are not just temporary discomfort but may leave long -term effects, especially for those who have a history of cancer.