Scientists are hoping a recent discovery will lead to new strategies for slowing or halting the lethal spread of skin cancer.
Research has shown a fatty molecule lays down a "breadcrumb trail" that allows malignant skin cancer to spread around the body.
Signals from the molecule, lysophosphatidic acid (LPA), help to make melanoma cells unusually aggressive and mobile.
Tests on laboratory cell lines and mice revealed how the tumour cells start their journey by breaking down a nearby source of LPA.
Once those molecules are depleted, the cells move out of the tumour in search of more. Each encounter with LPA prompts the cells to keep moving.
"Our exciting findings show that skin cancer cells create their own 'green light' signal to start spreading, and are lured to travel around the body by a trail of these fatty molecules" said Lead scientist Professor Robert Insall, from the Beatson Institute at the University of Glasgow.
"The next step will be to find how the melanoma cells break down the LPA molecules to see if this sparks ideas for new ways to stop the cancer from spreading. At the moment our research is still in early stages but we hope this could help doctors to make sure this cancer doesn't spread."
The research is published in the online journal Public Library of Science Biology.
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Skin cancer risk factors
Each year more than 13,000 people in the UK are diagnosed with melanoma and 2,200 die from the disease. Rates of melanoma are five times higher than they were 40 years ago.
Professor Nic Jones, chief scientist at Cancer Research UK, which funded Prof Insall's team, said: "Sadly there are few options available for patients whose melanoma has spread, which is especially concerning as this type of cancer has risen rapidly since the 70s.
"Research like this is crucial to find effective ways to limit the spread of tumours and increase the chances for more successful treatment of this horrible disease.
"We can all also reduce our risk of the disease by keeping safe in the sun. When the sun is strong it's best to cover up with clothes and spend time in the shade to protect your skin from sunburn and reduce your risk of skin cancer."