Rethinking cancer's ability to spread

8 December 2008

Many more skin cancer cells can cause tumours in other parts of the body than was previously thought, says a new study. Thousands of people are diagnosed with skin cancer every year. Could this latest research affect their treatment? Antenna investigates...

This research was published in the journal Nature on 4 December 2008.

Some cancer cells leave a tumour and cause cancer in other parts of the body.

Image: Elsa Quintana and Mark Shackleton

Until now scientists thought that only a few specialised cancer cells could trigger the growth of new tumours elsewhere in the body. So by getting rid of these cells you could stop cancer from spreading. But the latest research casts doubt on that idea...

Melanoma tumours are the most serious form of skin cancer.

Image: Timothy Johnson

Scientists can work out which cancer cells cause tumours by putting human skin cancer cells into mice then watching to see if tumours grow. The mice's immune system is suppressed so it doesn't kill the cancer cells before tumours can form.
In this study a team of US scientists suppressed a different part of the mice's immune system - natural killer cells. Scientist hadn't previously studied these cells in detail, because they thought that they didn't attack many cancer cells.

Previous studies had only partially knocked out the mice's immune systems.


What did they find?
'Knocking out the natural killer cells caused many more tumours to form. It turned out the natural killer cells were far more effective at destroying the tumour causing cancer cells than expected.' Sean Morrison, cancer researcher, University of Michigan
'Worryingly, we found that a quarter of the cancer cells in the mice had the potential to cause tumour growth - a staggering 250,000 times more than previous estimates.'

Sean Morrison, cancer researcher, University of Michigan.

Image: University of Michigan

What does this mean for cancer treatment?
'This area of cancer research is promising for potential treatments, but our findings show that we may need to target cancer cells in a different way,' explains Sean Morrison.
What do other experts think?
'This study looked at one particular type of skin cancer, but it may well have consequences for many other cancers. Scientists will have to look at this research cancer by cancer to design appropriate treatments.' Henry Scowcroft, Cancer Research UK

Henry Scowcroft, cancer treatment scientist, Cancer Research UK.

Image: Cancer Research UK