Reacción a "Respiratory viral infections activate metastatic breast cancer cells"

It is already known that an inflammatory response caused by a chronic infection (e.g. with the hepatitis C virus) can contribute to the development of cancer. What is new and interesting here is that acute respiratory infections can lead to the development of metastases due to the inflammatory response they cause.

To investigate this, the authors of the study used a mouse model in which they were able to demonstrate the proliferation of dormant metastatic cells due to the inflammatory response following influenza or SARS-CoV-2 infection. However, it was not shown whether the mice actually died more frequently or earlier from metastases after the infection. The effect also appears to be 10 to 100 times stronger after influenza infection than after infection with the SARS-CoV-2 virus adapted to mice – but this may also be due to the mouse model.

Regarding transferability to humans: The study proves that the general phenomenon can also be observed in humans. Of course, the authors cannot prove that it is the same mechanism, as these are epidemiological data.
"However, two independent cohorts show that breast cancer patients with a documented SARS-CoV-2 infection have a higher risk of dying from cancer or developing lung metastases than non-infected patients. Since only documented SARS-CoV-2 infection is examined as a variable, other factors such as stress or fewer visits to the doctor due to the pandemic can be ruled out, as these would also apply to non-infected patients. However, the effect is fortunately limited (approximately twofold, or a 44 percent increased risk in the other cohort). This means that breast cancer patients do not need to completely isolate themselves to prevent respiratory infection at all costs based on this data.

The effect was analysed in the early stages of the pandemic, when there were no vaccines and no Omicron variant. Therefore, the study does not take into account the possible protective effect of vaccination. Vaccination significantly reduces the risk of severe disease and thus of a severe inflammatory response after influenza or SARS-CoV-2 infection. It would therefore be expected that vaccination could also reduce the effect on metastasis formation.

Future studies should investigate this using the mouse model or other epidemiological data to gain an impression of how significant the metastasis-promoting effect of a respiratory infection really is in vaccinated breast cancer patients.‘
’In general, however, this study also shows that respiratory infections have other far-reaching effects in addition to their acute effect on the lungs. Other studies have already shown that the risk of cardiovascular diseases such as heart attacks is increased after a respiratory infection, and this study shows an effect on metastasis formation. These infections should therefore be taken seriously and people should protect themselves with available vaccinations against the disease and, hopefully, also against the secondary consequences.