LONDON (Reuters) - Scientists have discovered how cancer spreads from a primary site to other places in the body in a finding that could open doors for new ways of treating and preventing advanced disease.

Instead of a cell just breaking off from a tumor and traveling through the bloodstream to another organ where it forms a secondary tumor, or metastasis, researchers in the United States have shown that the cancer sends out envoys to prepare the new site.

Intercepting those envoys, or blocking their action with drugs, might help to prevent the spread of cancer or to treat it in patients in which it has already occurred.

In research reported in the journal Nature, Lyden and his colleagues describe what happens before the arrival of the cancerous cells at the new site.