Cancer road map shows how cancer spreads

Scientists at Cornell University in New York have discovered how cancer spreads from a primary site to other places in the body.

Their finding could open doors for new ways of treating and preventing advanced disease.

The researchers have found that 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, the cancer sends out envoys to prepare the new site.

They believe that by intercepting those envoys, or blocking their action with drugs, it might help prevent the spread of cancer or treat it in patients in which it has already occurred.

Professor David Lyden says they are basically looking at all the earlier steps that are involved in metastasis that they were not previously aware of.

He says that though the procedure is complex they are opening the door to all the things that occur before the tumor cell implants itself.

He compares it to a map showing where the metastasis will occur.

The ability of cancer to colonize other organs is what makes the disease so deadly, and once the disease has spread beyond its original site it is much more difficult to treat.

In their research Lyden and his colleagues describe what happens before the arrival of the cancerous cells at the new site.

Patricia Steeg, of the National Cancer Institute in Bethesda, Maryland, says the study shows that tumor cells can mobilize normal bone marrow cells, causing them to migrate to particular regions and change the local environment so as to attract and support a developing metastasis.

Cells at the site of the metastasis multiply and produce a protein called fibronectin, which acts like a glue to attract and trap the bone marrow cells to create a landing pad or nest for the cancer cells.

These so-called nests provide attachment factors for the tumor cells to implant and nurtures them and causes them not only to bind but to proliferate.

Lyden says once that all takes place there is a fully formed metastatic site or secondary tumor, but this is the first time anyone has discovered what he calls 'the pre-metastatic niche'.

It seems that without the landing pad, the cancerous cell could not colonize the organ.

In animal and laboratory studies, the scientists have looked at how breast, lung and oesophageal cancer spread.

The say the envoys from the tumor determine the site of the secondary site.

Lyden says by measuring the number of special bone marrow cells circulating in the body it might help to determine whether a cancer is likely to spread.

He believes the finding opens up the door to new concepts of how metastasis is taking place and an understanding of all the multiple processes will help the development of new drugs that block each step.

The research is reported in the journal Nature.