title: Comparative evaluation of cell-free tumor DNA in blood and disseminated tumor cells in bone marrow of patients with primary breast cancer.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  BM 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.
  
  
  RESULTS
  LOH 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 (> or = 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.
  
  
  CONCLUSIONS
  The detection of LOH on cell-free tumor DNA in blood is unrelated to BM micrometastasis and provides independent information on breast cancer progression.
authors.affiliation: Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg, 20246, Germany. hschwarz@uke.uni-hamburg.de
authors.forename: Heidi
authors.initials: H
authors.lastname: Schwarzenbach
authors.forename: Klaus
authors.initials: K
authors.lastname: Pantel
authors.forename: Birthe
authors.initials: B
authors.lastname: Kemper
authors.forename: Cord
authors.initials: C
authors.lastname: Beeger
authors.forename: Friedrich
authors.initials: F
authors.lastname: Otterbach
authors.forename: Rainer
authors.initials: R
authors.lastname: Kimmig
authors.forename: Sabine
authors.initials: S
authors.lastname: Kasimir-Bauer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001853:Bone Marrow / Q000473:pathology*; D001943:Breast Neoplasms / Q000097:blood / Q000235:genetics* / Q000473:pathology*; D016022:Case-Control Studies; D004273:DNA, Neoplasm / Q000097:blood* / Q000235:genetics; D005260:Female; D006801:Humans; D019656:Loss of Heterozygosity; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000235:genetics / Q000473:pathology; D016133:Polymerase Chain Reaction / Q000379:methods
chemical_list: D004273:DNA, Neoplasm