Detection of circulating tumor cells in peripheral blood of breast cancer patients during or after therapy using a multigene real-time RT-PCR assay

To evaluate the utility of a multigene real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay to detect circulating tumor cells in peripheral blood specimens of breast cancer patients during or after treatment. Using this assay, peripheral blood samples were analyzed for expression levels of mammaglobin and three complementary transcribed breast cancer-specific genes: B305D, gamma-aminobutyrate type A receptor pi subunit (GABA pi; GABRP), and B726P. We examined 172 blood specimens from 82 breast cancer patients during or after therapy for the presence of circulating tumor cells using the multigene real-time RT-PCR assay. In 63.4% of the blood samples, a positive signal for mammaglobin and/or three breast cancer-associated gene transcripts was detected. Of breast cancer patients, 75.6% had at least one positive blood sample. Blood specimens from 51 of 53 healthy female volunteers tested negative in the assay whereas two samples had a low expression signal. In addition, three patients were monitored for more than a year during their adjuvant therapy treatment. This assay could be a valuable tool for monitoring breast cancer patients during and after therapy.