title: Changing levels of circulating tumor cells in monitoring chemotherapy response in patients with metastatic breast cancer.
abstract: BACKGROUND
  The detection of >5 circulating tumor cells (CTCs)/7.5 ml blood in patients being treated for metastatic breast cancer (MBC) has recently been shown to be predictive for therapy efficacy. The aim of this study was to investigate whether changing CTC levels during the course of chemotherapy treatment would also be useful in monitoring response to treatment.
  
  
  METHODS
  CTC levels were determined in 58 MBC patients at the beginning and after 3 cycles of chemotherapy. Changes in CTC level (either negative CTCs (<5 CTCs/7.5 ml blood) turning positive, vice versa, or a change of ±25%) were correlated to radiologic Response Evaluation Criteria In Solid Tumors (RECIST) criteria, as well as serum CA 15-3 measurements, and were evaluated for their capability to predict survival.
  
  
  RESULTS
  Changing CTC levels significantly correlated with response to therapy as measured by radiologic RECIST criteria (p<0.001), and serum CA 15-3 level changes (p=0.017). Patients with decreasing CTC levels survived significantly longer than patients with increasing CTC levels (17.67±5.90 months versus 4.53±0.54 months, p<0.001).
  
  
  CONCLUSIONS
  The observation of changes in CTC level during the course of chemotherapy is useful in monitoring therapy efficacy and is correlated with overall survival. Further prospective trials should investigate the clinical usefulness of determining changes in CTC level during chemotherapy of MBC.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Tuebingen, Calwer Strasse 7, 72076 Tuebingen, Germany. andreas.hartkopf@med.uni-tuebingen.de
authors.forename: Andreas D
authors.initials: AD
authors.lastname: Hartkopf
authors.forename: Philipp
authors.initials: P
authors.lastname: Wagner
authors.forename: Diethelm
authors.initials: D
authors.lastname: Wallwiener
authors.forename: Tanja
authors.initials: T
authors.lastname: Fehm
authors.forename: Ralf
authors.initials: R
authors.lastname: Rothmund
mesh_terms: D000951:Antigens, Neoplasm / Q000097:blood; D001943:Breast Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000473:pathology*; D003710:Demography; D016903:Drug Monitoring; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D016896:Treatment Outcome
chemical_list: D000951:Antigens, Neoplasm