title: Assessment of circulating tumor cells and serum markers for progression-free survival prediction in metastatic breast cancer: a prospective observational study.
abstract: BACKGROUND
  Circulating tumor cells (CTC) have been recently proposed as a new dynamic blood marker whose positivity at baseline is a prognostic factor and whose changes under treatment are correlated with progression-free survival (PFS) in metastatic breast cancer patients. However, serum marker levels are also used for the same purpose, and no clear comparison has been reported to date.
  
  
  METHODS
  The IC 2006-04 enrolled prospectively 267 metastatic breast cancer patients treated by first line chemotherapy and confirmed that CTC levels are an independent prognostic factor for PFS and overall survival (OS). A secondary pre-planned endpoint was to compare prospectively the positivity rates and the value of CTC (CellSearch®), of serum tumor markers (carcinoembryonic antigen (CEA), cancer antigen 15.3 (CA 15-3), CYFRA 21-1), and of serum non-tumor markers (lactate deshydrogenase (LDH), alkaline phosphatase (ALP)) at baseline and under treatment for PFS prediction, independently from the other known prognostic factors, using univariate analyses and concordance indexes.
  
  
  RESULTS
  A total of 90% of the patients had at least one elevated blood marker. Blood markers were correlated with poor performance status, high number of metastatic sites and with each other. In particular, CYFRA 21-1, a marker usually used in lung cancer, was elevated in 65% of patients. A total of 86% of patients had either CA 15-3 and/or CYFRA 21-1 elevated at baseline. Each serum marker was associated, when elevated at baseline, with a significantly shorter PFS. Serum marker changes during treatment, assessed either between baseline and week 3 or between baseline and weeks 6 to 9, were significantly associated with PFS, as reported for CTC. Concordance indexes comparison showed no clear superiority of any of the serum marker or CTC for PFS prediction.
  
  
  CONCLUSIONS
  For the purpose of PFS prediction by measuring blood marker changes during treatment, currently available blood-derived markers (CTC and serum markers) had globally similar performances. Besides CEA and CA 15-3, CYFRA 21-1 is commonly elevated in metastatic breast cancer and has a strong prognostic value.
authors.affiliation: Department of Medical Oncology, Institut Curie, 26 rue d'Ulm, 75005 Paris, France.
authors.forename: François-Clément
authors.initials: FC
authors.lastname: Bidard
authors.forename: David
authors.initials: D
authors.lastname: Hajage
authors.forename: Thomas
authors.initials: T
authors.lastname: Bachelot
authors.forename: Suzette
authors.initials: S
authors.lastname: Delaloge
authors.forename: Etienne
authors.initials: E
authors.lastname: Brain
authors.forename: Mario
authors.initials: M
authors.lastname: Campone
authors.forename: Paul
authors.initials: P
authors.lastname: Cottu
authors.forename: Philippe
authors.initials: P
authors.lastname: Beuzeboc
authors.forename: Emilie
authors.initials: E
authors.lastname: Rolland
authors.forename: Claire
authors.initials: C
authors.lastname: Mathiot
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Pierga
mesh_terms: D000951:Antigens, Neoplasm / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood / Q000401:mortality / Q000473:pathology*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D053539:Keratin-19 / Q000097:blood*; D008875:Middle Aged; D018396:Mucin-1 / Q000097:blood*; D015999:Multivariate Analysis; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D011446:Prospective Studies; D018709:Statistics, Nonparametric
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D053539:Keratin-19; D018396:Mucin-1; C102012:antigen CYFRA21.1