Comparative evaluation of cell-free tumor DNA in blood and disseminated tumor cells in bone marrow of patients with primary breast cancer

Abstract

IntroductionThe origin and clinical relevance of circulating cell-free tumor DNA in the blood of cancer patients is still unclear. Here we investigated whether the detection of this DNA is related to bone marrow (BM) micrometastasis and tumor recurrence in breast cancer patients.MethodsBM aspirates of 81 primary breast cancer patients were analyzed for the presence of disseminated tumor cells (DTC) by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3. PCR-based fluorescence microsatellite analysis was performed for detection of loss of heterozygosity (LOH) at 6 polymorphic markers using cell-free serum DNA. The data were correlated with established risk factors, and patients were followed-up over 6-10 years.ResultsLOH was detected in 33.5% of blood samples. The occurrence of LOH at the entire microsatellite marker set correlated with histopathology (P = 0.05) and grading (P = 0.006) of the primary tumor. The genomic region characterized by marker D9S171 was only affected by LOH in patients with increased tumor stages (pT2-4, P < 0.05) and older age (≥ 55 years, P = 0.05). Kaplan-Meier analysis showed that LOH at D3S1255 (P = 0.009) and D9S171 (P = 0.001) were significantly associated with tumor relapse. In BM, DTC were detected in 39.5% of the patients, and this finding correlated with distant metastases (P < 0.05). Patients with DTC-positive BM had higher DNA yields in their blood than patients with DTC-negative BM (P < 0.05). However, no significant correlations were found between the presence of DTC in BM and the detection of marker-specific LOH on blood DNA.ConclusionsThe detection of LOH on cell-free tumor DNA in blood is unrelated to BM micrometastasis and provides independent information on breast cancer progression.

Genomic analysis of circulating cell-free DNA infers breast cancer dormancy

“…Several groups, including ourselves, have reported that measuring circulating tumor cells (CTCs), bone marrow, or total circulating DNA can help in this regard (Meng et al 2004;Braun et al 2005;Slade et al 2005;Schwarzenbach et al 2009), but we and others only find one to two cells in 7.5 mL blood intermittently present, and other tests aimed at either increasing the number of cells detected or quantifying DNA size or other more straightforward characteristics thus far have not proved sufficiently reliable for clinical use. The results of this study suggest plasma cfDNA analysis is potentially more informative.…”

Relevance of circulating tumor cells, extracellular nucleic acids, and exosomes in breast cancer

“…Evidence of extracellular nucleic acids in cancer Extracellular nucleic acids, specifically extracellular DNA (exDNA), were first described in human plasma/serum by Mandel [61]. Similarly the presence of exRNA is well documented in sera/plasma from patients presenting with breast [62][63][64] and colon cancers [65,66].…”

Organ Specific Tumor Markers: What’s New?

“…[29]. Certain markers like DNA ploidy by flow cytometry [30], p53 [31], cathepsin D [32], cyclin E [33], proteomics [34], detection of bone marrow micrometastases [35], and circulating tumor cells (CTCs) [36] are considered, but no evidence is available which would recommend them for routine clinical use. Breast cancer markers are summarized in Table 4. BRCA1/2 gene mutations have been described in familial breast cancer patients.…”

“…Bone marrow micrometastases as markers for breast cancer are a new topic to the guidelines [35]. Currently available evidence is insufficient to recommend evaluation of bone marrow micrometastases for management of patients with breast cancer.…”