Scientists discover how cancer spreads
December 09 2005 1:00 AM ET
discovered how cancer—particularly a deadly form of
the disease like breast cancer--spreads from a primary
site to other places in the body. Their findings could
open doors for new ways of treating and preventing
Instead of a cell
just breaking off from a tumor and traveling through
the bloodstream to another organ where it forms a secondary
tumor—a process called
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 help to treat it in patients in which it has
"We are basically
looking at all the earlier steps that are involved in
metastasis that we weren't previously aware of. It is
complex, but we are opening the door to all these
things that occur before the tumor cell implants
itself," said professor David Lyden of Cornell University.
"It is a map to where the metastasis will occur.”
to colonize other organs is what makes the disease so
deadly. Once the cancer has spread beyond its original site
it is much more difficult to treat.
reported in the journal Nature, Lyden and his
colleagues describe what happens before the arrival of the
cancerous cells at the new site. "The authors show 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," Patricia Steeg of the
National Cancer Institute in Bethesda, Md., said in a
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 nests provide attachment
factors for the tumor cells to implant and nurture
them. It causes them not only to bind but to proliferate.
Once that all takes place, we have a fully formed
metastatic site or secondary tumor," said Lyden.
landing pad, the cancerous cell could not colonize the
In animal and
laboratory studies, the scientists looked at how breast,
lung, and esophageal cancer spread. The envoys from the
tumor determine the site of the secondary site. Lyden
said measuring the number of special bone marrow cells
circulating in the body could help to determine
whether a cancer is likely to spread.
"This opens up
the door to new concepts of how metastasis is taking
place. If we can understand all these multiple processes, we
can develop new drugs that block each step. That way
we have a much better future than just trying to treat
the tumor cell, which is almost like a last step in
this process.” (Reuters)
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