title: Circulating tumor cells: a useful predictor of treatment efficacy in metastatic breast cancer.
abstract: OBJECTIVE
  Five or more circulating tumor cells (CTCs) per 7.5 mL of blood predicts for poorer progression-free survival (PFS) in patients with metastatic breast cancer (MBC). We conducted a prospective study to demonstrate that CTC results correlate strongly with radiographic disease progression at the time of and in advance of imaging.
  
  
  METHODS
  Serial CTC levels were obtained in patients starting a new treatment regimen for progressive, radiographically measurable MBC. Peripheral blood was collected for CTC enumeration at baseline and at 3- to 4-week intervals. Clinical outcomes were based on radiographic studies performed in 9- to 12-week intervals.
  
  
  RESULTS
  Sixty-eight patients were evaluable for the CTC-imaging correlations, and 74 patients were evaluable for the PFS analysis. Median follow-up was 13.3 months. A statistically significant correlation was demonstrated between CTC levels and radiographic disease progression in patients receiving chemotherapy or endocrine therapy. This correlation applied to CTC results obtained at the time of imaging (odds ratio [OR], 6.3), 3 to 5 weeks before imaging (OR, 3.1), and 7 to 9 weeks before imaging (OR, 4.9). Results from analyses stratified by type of therapy remained statistically significant. Shorter PFS was observed for patients with five or more CTCs at 3 to 5 weeks and at 7 to 9 weeks after the start of treatment.
  
  
  CONCLUSIONS
  We provide, to our knowledge, the first evidence of a strong correlation between CTC results and radiographic disease progression in patients receiving chemotherapy or endocrine therapy for MBC. These findings support the role of CTC enumeration as an adjunct to standard methods of monitoring disease status in MBC.
authors.affiliation: Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20007-2198, USA. liumc@georgetown.edu
authors.forename: Minetta C
authors.initials: MC
authors.lastname: Liu
authors.forename: Peter G
authors.initials: PG
authors.lastname: Shields
authors.forename: Robert D
authors.initials: RD
authors.lastname: Warren
authors.forename: Philip
authors.initials: P
authors.lastname: Cohen
authors.forename: Mary
authors.initials: M
authors.lastname: Wilkinson
authors.forename: Yvonne L
authors.initials: YL
authors.lastname: Ottaviano
authors.forename: Suman B
authors.initials: SB
authors.lastname: Rao
authors.forename: Jennifer
authors.initials: J
authors.lastname: Eng-Wong
authors.forename: Francoise
authors.initials: F
authors.lastname: Seillier-Moiseiwitsch
authors.forename: Anne-Michelle
authors.initials: AM
authors.lastname: Noone
authors.forename: Claudine
authors.initials: C
authors.lastname: Isaacs
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000473:pathology*; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D018189:Immunomagnetic Separation; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents