'This suggests that anti-macrophage therapy will have an impact in patients even with metastatic disease,' Pollard said.

Based on this new work, he added: 'Macrophages themselves, or their unique signalling pathways, represent new therapeutic targets that may be efficacious in reducing cancer mortality.'

Ordinarily, macrophages are vital for maintaining health as an integral arm of the immune system, one of the body's main lines of defence.

Their assigned tasks include cleaning up debris in the wake of disease or injury, alerting other immune system cells when an infection begins, and helping identify viruses and bacteria that need to be killed, said an Einstein release.

'This new study is important because it definitively shows the effects of macrophages at distant sites, as well as the identity of the macrophage population,' Pollard explained.

The new study was published online in PLoS ONE.