Researchers in Canada say they have identified possible reasons why breast cancer tumours often spread to the lungs.
In laboratory experiments they noted that breast cancer stem cells (CSCs) have a particular inclination for migrating towards and growing inside the lung.
They also identified a process − that could be disrupted − in which specific interactions take place between breast CSCs and proteins from the lungs, they report online in the journal Neoplasia.
By disrupting this process they suggest it may be possible to reduce the ability of breast cancer to spread, or metastasise.
Lead researcher Dr Alison Allan, an associate professor at the University of Western Ontario, noted a theory known as the “seed and soil” hypothesis, which has gained traction in the study of metastasis.
She used the analogy of the seeds of a dandelion blowing across different areas but not all of those seeds grow where they land – the soil in which they find themselves must be sufficiently nutritious so it is conducive to growth.
In metastasis, the tumour cells or “seeds” have some inherent properties determining their ability to flourish elsewhere, but likewise the other organs in the body − the “soil” − may be more attractive sites for tumours to grow, she explained.
Dr Allan said less research has been devoted to the “soil” side of the equation because the cancer cells themselves are easier to analyse.
She said the particular proteins produced in the lung that her team has identified seem to be key to making the lung a convenient home for the cancer cells to grow due to the way they interact with CSCs.
The hope is that the team’s findings will lay the foundations for the improved treatment of breast cancer.
In addition it is said to have prepared the ground for new clinical studies investigating whether a higher number of breast CSCs in the primary tumour could make it more likely for lung metastasis to occur in some patients − and if so whether the early detection of this fact could aid successful treatment.