Scientists have discovered that common respiratory infections, including Covid and influenza, possess the ability to reactivate cancer cells lying dormant within the body, prompting their rapid dissemination.

The infections can rouse what are known as disseminated cancer cells - malignant cells that have separated from original tumours and migrated to remote organs where they remain inactive, sometimes for years.

The latest findings demonstrate how viral respiratory illnesses may accelerate cancer progression by disturbing these sleeping cells.

Published in the journal Nature, the study warns of previously unrecognised risks associated with common infections for cancer patients and survivors.

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The study highlights previously unrecognised risks associated with common infections

Experiments conducted on mice demonstrated that exposure to Covid or influenza viruses led to an explosive proliferation of metastatic cells throughout the lungs mere days after infection.

The research team observed that visible metastatic lesions emerged in the animals within a fortnight of viral exposure.

This rapid progression occurred through the body's inflammatory response - a natural defence mechanism triggered when the immune system detects and combats infections.

The inflammation process proved capable of rousing cancer cells from their dormant state, transforming them from inactive threats into actively spreading malignancies.

These findings suggest respiratory infections may pose particular dangers for individuals with histories of cancer.

The research team's analysis pinpointed interleukin-6 (IL-6) as the crucial protein responsible for rousing these dormant cancer cells.

IL-6 is produced by immune cells as part of the body's standard response to infections or tissue damage.

During respiratory infections, elevated levels of this protein appear to send signals that prompt inactive cancer cells to resume their malignant activity.

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This discovery provides the first clear mechanism explaining how common viral infections might accelerate cancer recurrence or progression.

Understanding IL-6's role opens potential avenues for protecting cancer patients from infection-triggered metastases, though further research remains necessary to develop practical interventions.

The discovery comes as a leading cancer specialist has cautioned that sore throats persisting beyond three weeks might indicate head or neck cancer instead of typical viral infections.

The specialist noted that when throat pain continues despite standard remedies, further investigation becomes crucial.