Detection of circulating mammary carcinoma cells in the peripheral blood of breast cancer patients via a nested reverse transcriptase polymerase chain reaction assay for mammaglobin mRNA

Purpose: According to current medical research, mammaglobin (hMAM) is expre ssed exclusively in the mammary glands of adult women and in mammary tumor cell lines. Therefore, we examined hMAM expression as a marker for the dete ction of carcinoma cells in the peripheral blood of patients with breast ca ncer (BC). Patients and Methods: Blood samples obtained from 114 BC patients at the va rious stages of their disease and from 68 individuals without BC were scree ned for hMAM mRNA by a nested reverse transcriptase polymerase chain reacti on (RT-PCR) assay. Results: The assay exhibited a calculated analytical limit of one tumor cel l per 10(6) to 10(7) WBCs, None of the samples from peripheral blood of 27 healthy individuals were positive, whereas 29 (25%) of 114 samples from BC patients were positive for hMAM mRNA. hMAM mRNA expression was detected in five (28%) of 18 BC patients at diagnosis, in three (6%) of 53 with no evid ence of disease, and in 21 (49%) of 43 with metastatic disease. These resul ts correlate with patients' carcinoembryonic antigen (CEA) plasma level and , to some extent, with estrogen receptor status. Two of 41 samples from pat ients with malignancies other than BC were also positive. Conclusion: In contrast to healthy volunteers, hMAM transcripts were detect ed in the peripheral blood of BC patients. The percentage of positivity rel ates to the clinical stages of disease, CEA plasma level, and estrogen rece ptor status. Aberrant hMAM expression might occur occasionally in malignanc ies other than BC. The clinical relevance of hMAM RT-PCR-based tumor cell d etection in the peripheral blood of BC patients should be further evaluated in prospective studies. (C) 1999 by American Society of Clinical Oncology.