Cancer cell stickiness may indicate how likely tumours are to spread around the body, research has shown.
The discovery could pave the way to a much-needed test for deadly cancers with a high risk of migrating to vital organs such as the liver or brain.
Cancer spread, or metastasis, is the major reason why people die from the disease.
Many cancers remain non-life threatening as long as they stay in one place, but transform into killers when they colonise other parts of the body.
Scientists have now shown that weakly sticky cancer cells are more likely to invade other tissues than those with strong adhesion.
The US team designed a spinning disc device that could measure the adhesion strength of breast and prostate cancer cells with varying levels of metastatic potential.
Metastatic cells were found to share very similar levels of stickiness, and strongly adherent cells were less likely to spread.
Lead researcher Dr Adam Engler, from the University of California at San Diego, said: "There is no common biological marker that says that a tumour is more likely to spread.
"However, our device shows that there may in fact be a physical marker that is predictive of the likelihood of spreading."
Only a small subset of cancer cells from a tumour or even a cultured cell line is capable of spreading and forming "secondary" tumours.
The stickiness test was able to identify cells from metastatic cell lines that appeared reluctant to spread and behaved more like cells from non-metastatic cell lines.
Building on the results, published in the Biophysical Journal, the scientists have developed a new device that isolates weakly sticky migratory cells.
Future mouse studies will investigate whether these cells form secondary tumours at a higher rate than a general population of tumour cells.
Co-author Pranjali Beri, also from the University of California at San Diego, said: "If we find a correlation between low numbers of weakly adherent tumour cells in the tissue surrounding a tumour and long cancer-free survival times, we believe that this could serve as an indicator for metastatic potential of the patient's tumour."