Highly sensitive detection of the MGB1 transcript (mammaglobin) in the peripheral blood of breast cancer patients

We describe a new one-step RT-PCR assay for the detection of the mammaglobin (MGB1) gene transcript in the peripheral blood of breast cancer patients. With this approach, the MGB1 transcript could be detected in the peripheral blood of 22 of 54 (41%) breast cancer patients prior to any therapy. This method, using specific primers for cDNA synthesis, proved to be more sensitive (10(-6) to 10(-11), usually 10(-7)) than previously reported methodologies. This increased sensitivity was achieved without compromising specificity, as the MGB1 transcript was not detected in 38 blood samples of healthy donors and in only 1 of 18 blood samples of patients presenting with hematologic malignancies. A positive correlation was seen between MGB1 positivity and breast cancer stage: 0/3 (0%) in stage 0, 3/13 (23%) in stage I, 6/17 (35%) in stage II, 5/10 (50%) in stage III, 8/11 (73%) in stage IV (p = 0.003). The prognostic and therapeutic implications of MGB1 positivity by one-step RT-PCR in the peripheral blood of breast cancer patients, especially in clinically localized disease (stages I and II), should be evaluated after long-term clinical follow-up of these patients.