Evaluation of mRNA markers for micrometastases detection by RT-PCR in lymph nodes (LN), peripheral blood (PB) and bone marrow (BM) of breast cancer patients (pts)

Abstract

20068 Background: Previous RT-PCR study showed that hMAM and CEA mRNA could be detected in 95% and 78% breast carcinomas, respectively. Analyzed in normal LN, these two markers were the only ones not expressed, compared to other mRNA markers which could be detected in a variable number of cases (Marchetti 2001). We evaluate the expression of CEA and hMAM mRNA in breast cancer pts in order to investigate if the identification of these transcripts could be correlated to in the LN, PB and BM. Methods: Tumor, normal gland, LN and PB were obtained from 49 breast cancer pts who have been referred to surgery during the period of Jun/2000 to Jan/2004.BM could be obtained from 21 of these cases. Before the manipulation of the tumor, 5 mL of PB was collected and 5 mL of BM was aspirated from the iliac crest. First level axillary LN were sectioned in two. One of the halves was immediately frozen in liquid nitrogen. CEA and hMAM transcripts have been analysed by RT-PCR. Results: Tumors were positive for CEA in 38 (77.6%) cases and LN were positive in 15 cases (36.7%). 6/49 pts expressed CEA in normal breast (12.2%). Five of these, tumor also expressed CEA. Two pts (4.1%) showed CEA expression in PB and in BM. One patient expressed CEA in BM but not in PB. All pts that showed expression in PB, BM and LN, also showed transcript of CEA in tumor. hMAM transcripts were found in 39 (79.6%) normal gland tissue and in 41 of tumor samples (85.7%). LN were positive to hMAM in 12 cases (24.5%). 5 of these (10.2%) were also positive in PB and BM samples. The pts showing hMAM expression in PB, BM and LN also showed its expression in neoplasic tissue. Analyzing both markers, two pts showed the expression of CEA and hMAM in the PB and BM samples. In 21 of the 49 cases the comparison of hMAM and CEA was possible to be performed in all tissues. CEA and hMAM expression associated to larger number of LN affected. Conclusions: CEA and hMAM transcripts can be detected in majority of breast cancer tissue. Specificity of hMAM seems to be higher than CEA, which can be detected in more than 10% of non-tumor breast tissue. Synchronicity of CEA or hMAM expression in the tumor and in extra-mammary sites was high, suggesting that these markers may provide an interesting strategy for follow-up micrometastatic disease. No significant financial relationships to disclose.