Purpose: To investigate and compare the diagnostic value of the detection of cytokeratin 19 (CK-19), carcinoembryonic antigen (CEA) and maspin mRNA by nested RT-PCR in the peripheral blood of women with breast cancer.
Materials and methods: The tumor cell lines MCF-7 and LOVO were used in an experimental tumor cell dilution model to determine the sensitivity of the nested RT-PCR for the 3 detection markers. RT-PCR analysis was performed in the peripheral blood of 54 healthy female blood donors, 28 patients with hematological malignancies, 31 with metastatic colorectal cancer, 75 with operable and 50 with metastatic breast cancer before receiving any cytotoxic chemotherapy, as well as in the bone marrow aspirates of 61 breast cancer patients.
Results: Nested RT-PCR for CK-19 mRNA presented the highest sensitivity by detecting 1 tumor cell amongst 10(6) PBMC in 4 out of 5 experiments. CK-19 mRNA was detected in the peripheral blood of 3.7% of female blood donors, 14.3% of hematological malignancies, 32% of operable and 42% of metastatic breast cancer patients. CEA mRNA was undetectable in the blood of female blood donors but was detected in blood samples of 3.5% of hematological malignancies, 19.3% of colorectal cancer and 10% of breast cancer patients. Maspin mRNA was undetectable in the blood of female blood donors, patients with hematological malignancies and colorectal cancer but was detected in 9.3% of operable and 14% of metastatic breast cancer patients. Maspin mRNA positivity correlated with tumor size in patients with early stage breast cancer (p = 0.057). The detection rates of CK-19 and maspin mRNA in bone marrow aspirates were 33% and 11% for operable and 62% and 9% for metastatic breast cancer, respectively. During follow-up, 27.4% of blood samples were positive for CK-19 mRNA versus 10.7% for maspin mRNA in patients with operable breast cancer with a concordance rate of only 12.7% for positives and 86% for negatives.
Conclusion: RT-PCR positivity for CK-19 mRNA is the most sensitive detection marker for occult tumor cells in operable and metastatic breast cancer, although nested RT-PCR for maspin mRNA appears to be more specific.