ERBB2 and neoplasm: A study comparing three different CTC detection methods in metastatic breast cancer patients found that a molecular technique based on a combined quantitative reverse-transcription polymerase chain reaction (qRT-PCR) approach for CK-19 and mammaglobin was more sensitive than the CellSearch® system or the AdnaTest BreastCancer®, which is another commercially available CTC assay based on the detection of three tumor-associated transcripts (GA733-2, MUC-1, and HER2) using the reverse transcription-polymerase chain reaction (RT-PCR) after immunomagnetic enrichment of tumor cells [37].