- A subset of CTCs occurring at low frequency are responsible for metastasis
- the frequency of occurrence in the reported study was 0 .6 to 33% of CTCs
- This subset is positive for CD44, CD47, MET
- experimental method involved isolating CTCs from 350 breast cancer patients using cell surface markers and transplating them in mice with defective immune system
- As the disease advances, the number of triple-positive cells increases, but the total number of CTCs does not.
- Patients with very high numbers of triple-positive cells had particularly high numbers of metastases and a much poorer prognosis than women in whom only few of these metastasis-inducing cells were detected
Conclusion: "On the whole, triple-positive cells seem to have a substantially higher biological relevance for disease progression than previously studied CTCs"