After receiving a breast cancer diagnosis, a person’s outlook is influenced by several factors – the most important of which is the extent of the cancer and whether it has spread beyond the original site of the tumour.
As a result, more and more researchers have been focusing on the process of metastasis in the hope that a better understanding of it will lead to better strategies for prevention.
New research, published in the journal Nature Cell Biology, sheds such light on the process of metastasis in breast cancer, uncovering a previously unknown aspect of it.
Primary breast tumours, the new study shows, have the ability to stop themselves from spreading.
The scientists who conducted the research were jointly led by Dr Sandra McAllister, from Brigham and Women’s Hospital and Harvard Medical School, both in Boston, MA, and Dr Christine Chaffer, from the Garvan Institute of Medical Research in Sydney, Australia.
Tracking down ‘breakaway cancer cells’
With their team, Drs McAllister and Chaffer conducted experiments in mice and human tumours. In a rodent model of breast cancer, they found that primary tumours have the ability to stop the ‘breakaway’ cancer cells from traveling to other sites in the body.
The primary tumour does this by triggering an inflammatory response from the immune system. Once activated, the immune system dispatches ‘search patrols’ of immune cells throughout the body. The main role of these cells is to find the locations where breakaway cells may be trying to settle and create new tumours.
According to Dr Chaffer, “When these breakaway cells are settling, before they have established a new tumour, they are particularly vulnerable, because they are in an intermediate state, and their identity isn’t very solid. It’s at this point that the immune system can intervene.”
The experiments showed that once the breakaway cells are tracked down, immune cells are able to ‘freeze’ them, thereby stopping metastasis.
“When breakaway cells are forced to remain in the transition state, they don’t grow very well,” adds Dr McAllister, “and their ability to form a new tumour is severely compromised.”
“So, remarkably, by activating the immune response, the primary tumour essentially shuts down its own spread,” said Dr Sandra McAllister.
Freezing secondary cancers in humans
The researchers were able to find confirmation for their initial findings in humans. An analysis of 215 people who had been diagnosed with advanced breast cancer revealed that those who displayed the same type of immune response had better survival rates than patients who did not exhibit the same immune response.
“We want to understand exactly what the tumour is releasing to activate this immune response, and how immune cells are targeting the secondary sites,” Dr Chaffer says, going on to explain how the findings can be used to stop advanced breast cancer from spreading.
“In principle, all of these steps present therapeutic opportunities that could be used to stop a cancer from developing any further.”
“When you have a primary tumour,” she says, “there are untold numbers of breakaway cells that will travel throughout the body – but not all of them will form tumours.”
“By some estimates, less than 0.02 per cent of breakaway cells will form secondary tumours, so we have a real opportunity to bring this number down to zero.”
“This new research has yielded that rare thing,” continues Dr Chaffer, “A clue from the cancer itself about new possibilities to fight its spread.”
“Our goal is to work out how we can mimic this ‘freezing’ of secondary cancers, so that one day we might influence all breast cancers to keep their secondary tumours in check,” said Dr Christine Chaffer
Source: Medical News Today