title: New Approach for Interpreting Changes in Circulating Tumour Cells (CTC) for Evaluation of Treatment Effect in Metastatic Breast Cancer.
abstract: OBJECTIVE
  Attempts have been made to use CTC values for interpretation of treatment response and to guide change of chemotherapy by using a static cut-off of 5 CTC to stratify patients in favourable or unfavourable responders. We propose a new approach to interpret treatment effect using significant changes in CTC values (SCV-limits(1)) as grouping parameter for responders and non-responders to chemotherapy among metastatic breast cancer (mBC) patients.
  
  
  METHODS
  CTC were analysed using the CellSearch System in blood from 47 mBC patients before the start of new chemotherapy and before the third cycle of therapy. The new and old approach to interpret changes in CTC values were compared in relation to progression free survival (PFS).
  
  
  RESULTS
  The new approach using significant CTC change (P = .032) and the old approach using static cut-off (P > .001) correlated significantly with PFS using a cohort of 47 patients.
  
  
  CONCLUSIONS
  We propose a new approach to interpret significant changes between baseline and follow-up CTC values as a tool for assessing treatment effect in mBC. Our approach stratified patients in new risk groups that were stratified significantly with respect to PFS. More patients are needed to balance the size of the risk groups for better comparison to the existing approach based on a 5 CTC cut-off.
authors.affiliation: Department of Clinical Immunology and Biochemistry, Lillebaelt Hospital, Vejle, Denmark.
authors.forename: Peer
authors.initials: P
authors.lastname: Horn
authors.affiliation: Department of Clinical Oncology, Lillebaelt Hospital, Vejle, Denmark.
authors.forename: Erik Hugger
authors.initials: EH
authors.lastname: Jakobsen
authors.affiliation: Department of Clinical Immunology and Biochemistry, Lillebaelt Hospital, Vejle, Denmark.
authors.forename: Jonna Skov
authors.initials: JS
authors.lastname: Madsen
authors.affiliation: Department of Clinical Immunology and Biochemistry, Lillebaelt Hospital, Vejle, Denmark.
authors.forename: Ivan
authors.initials: I
authors.lastname: Brandslund