A major study, published in August 2025 in the prestigious Jama medical journal, brings to light new data, which can change the way in which the effects of infections to the survivors cancer. As stated, during the first year of its pandemic COVID-19references to unusually increased incidents of people who suddenly had metastatic cancer, mainly of the Breast and intestine.
The explanation attributed the phenomenon to delays of medical examinations and treatments Due to the pandemic, which resulted in diagnoses being more advanced. However, as the Intensive Care Professor at the University College London, Hugh Montgomery, pointed out, “cancers do not evolve like that, 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?
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. But when mice were exposed to a mild dose of influenza virus, the researchers noticed that in 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 “Impressive increase” of cancer cells.
“The viral infection greatly accelerates the growth of these cells,” said John Alcorn, a 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, UK Biobank, which included more than 4,800 cancer patients in recession, found that those who had Positive COVID-19 TEST 2020 had almost Double 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 ill by Covid-19s showed increased chance of developing metastases to the lungsconfirming the findings of experiments in mice.
Influenza and Covid -9 cause severe inflammation in the body, as the immune system is trying 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, IL-6 appeared to be a key factor in awakening cancer cells. But even when her levels returned to normal 15 days after the infection, the cells continued to grow, suggesting that they exist and 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 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.
The result of the research was brought to light by the Professor of Therapeutics – Epidemiology – Preventive Medicine, Pathologist (NCAF School of Medicine, Theodora Psaltopoulou Hospital), Biologist Alexandra Stavropoulou, Dr. Maria Kaparelou (Pathologist-Oncologist) and Thanos Dimopoulos (T. Rector of EKPA, Professor of Therapeutic-Oncology-Hematology, Director of Therapeutic Medical School of Nursing School, Alexandra Hospital).