The team at Cold Spring Harbor Laboratory (CSHL) in New York focused on a process called ‘vascular mimicry', where cancer cells form their own network of tubes similar to blood vessels.
They identified two genes that produce proteins called Serpine2 and Slpi. These proteins helped maintain a blood supply to a breast cancer tumor in mice.
Mimicking blood vessels in this way helped the disease spread to other parts of the body, and provides the tumor with the oxygen and nutrients it needs grow.
Dr Alan Worsley, senior science communications officer at Cancer Research UK, said that the two protein molecules help prevent the blood from clotting.
"This allows oxygen and nutrients to reach the tumor and helps tumor cells get into the bloodstream and spread to other parts of the body," he said.
These same genes have also previously been found to be switched on in patients whose cancers have spread to the lungs.
When the researchers decreased the amount of Serpine2 or Slpi inside the breast cancer cells they were able to reduce the amount of cancer cells escaping to other parts of the body.
It is hoped that targeting the proteins could curb the spread of breast cancer and ultimately lead to the development of new treatments.
But Dr Worsley cautioned that the research was still at an early stage.
"More research is needed to see whether drugs that target these molecules would benefit patients. But understanding how cancers spread is crucial for developing new treatments to stop it." he said.
A different group of drugs, called angiogenesis inhibitors, have already been developed as potential treatments by preventing the formation of new blood vessels. Tumours need new blood vessels to help them grow and spread, but these drugs have not been as successful as hoped.
The researchers believe that vascular mimicry could be one of the reasons behind this.
Lead author on the study, Dr Elvin Wagenblast, speculated that "targeting angiogenesis and vascular mimicry at the same time could help produce better results in patients in the long run."
The study is published in the journal Nature.
Source: Cancer Research UK