People with non-metastatic, operable breast cancer who have circulating tumour cells (CTCs) before chemotherapy have lower levels of progression-free and overall survival than those in whom CTCs are not found, research has shown. Authors of the small study, published today in The Lancet Oncology, say that assessment of circulating tumour cells might in future provide important prognostic information in early breast cancer.
It was already known that the presence of CTCs is associated with poor prognosis in patients with metastatic breast cancer, but the authors wanted to know whether the identification of CTCs could also be of prognostic value in non-metastatic breast cancer.
The researchers recruited 302 people with operable, stage 1-3 breast cancer who had not yet undergone chemotherapy. At the point of primary tumour surgery – but before the tumour had been surgically manipulated – they collected 7.5ml of peripheral blood.
In almost a quarter (24%) of patients, at least one CTC was found in the blood sample; 10% of patients’ samples contained two or more CTCs, and 5% contained three or more CTCs.
There was a strong correlation between the presence of CTCs and patients’ progression-free and overall survival: 15% of patients whose samples contained CTCs relapsed, and 10% died, during the study period, compared with 3% and 2% respectively of patients with no CTCs found in their blood samples. Almost a third (31%) of patients whose samples contained three or more CTCs died or relapsed during the same period.
The authors said: “Both progression-free and overall survival were worse in patients with one or more circulating tumour cells … the growing body of published work, including our study, suggests that assessment of circulating tumour cells might provide important prognostic information in these patients.
“If the presence of circulating tumour cells were to contribute independently to the currently available prognostic factors, this information might be useful in disease staging and in identifying patients who might benefit from additional adjuvant therapies.”
Because it is still poorly understood how chemotherapy affects CTC concentration, and this study included only chemotherapy-naive patients, the authors say that further research will have to examine whether or not CTC analysis could become a useful diagnostic tool for early-stage breast cancer.
Professor Justin Stebbing, from the department of surgery and cancer at Imperial College London, agreed in his accompanying editorial that more research is needed. He wrote: “…at present we are in a difficult situation where we have a reliable prognostic biomarker but restricted guidance on how this information should be used, and therefore, until the completion of further studies, we do not envisage patients being treated differently on the basis of these data”.