Dutch researchers have shown that an antibody-based test called CellSearch, which is used to detect circulating breast cancer cells in patients before and during treatment, may not detect all subtypes of breast cancer.
A research team led by Dr. Anieta Sieuwerts, of the Erasmus Medical Center in Rotterdam, The Netherlands, has identified five subtypes of breast cancer by their gene expression patterns-namely basal, HER2-positive, luminal A and B, and normal-like.
The researchers say that these subtypes vary in their natural history and response to therapy.
Studies conducted in the past suggested that women who had a decrease in circulating tumour cells after the start of treatment were likely to have a better outcome than those who did not have a decline.
However, according to the researchers, it was not known whether the CellSearch assay detected all five subtypes of cancer equally.
In the current study, Sieuwerts' team tested cells from a total of 34 cell lines that represented a mix of the five breast cancer subtypes.
The researchers found that the assay did not detect the nine normal-like breast cancer cells but did detect the other subtypes.
"New tests that include antibodies that specifically recognize normal-like breast tumor cells...are needed," the authors conclude.
The study has been reported in the Journal of National Cancer Institute.