COUNTING breast cancer cells in the blood may help predict a woman's survival chances and aid targeted treatment, a new study shows.
Patients with at least five circulating tumour cells (CTCs) detected straight after surgery had a four-fold increased risk of cancer recurrence, scientists found.
They were also three times more likely to die from their disease than women without CTCs.
But doctors believe it is not all bad news for women with circulating tumour cells.
Identifying the cells could make it possible to spot early disease changes and provide the most effective treatment.
Circulating tumour cells are rare and difficult to detect. In cancer patients, one millilitre of blood contains an estimated 7.5 tumour cells compared with a few million white blood cells and a billion red blood cells.
The German scientists conducting the new study used advanced automated technology to find CTCs in blood samples. The blood test is much less invasive than the alternative way of detecting CTCs in bone marrow.
Researchers tested the blood of more than 2,000 patients all of whom had undergone surgery before starting chemotherapy treatment.
CTCs were detected in 21.5pc of the blood samples, a much lower rate than that usually seen in advanced and spreading breast cancer.
Study leader Dr Bernadette Jager, from Munich, said: "Although there is currently no direct advantage to the patient of knowing her CTC status, this is already a step forward, and in future we believe that the presence of CTCs could be used as a marker for monitoring the efficacy of treatment.
"If this proves to be the case, it will also help us determine the best chemotherapy regime for each patient."
Dr Jager presented the findings at the European Breast Cancer Conference (EBCC) in Vienna. CTC detection could be combined with routine blood tests and carried out frequently, she said.