title: Circulating tumor cell assays for the prognosis of prostate and colon cancers.
abstract: BACKGROUND
  Diagnostic testing for circulating tumor cells (CTCs) in peripheral blood is making the transition from the research setting to clinical practice. Measurement of CTCs may assist clinicians in making important clinical decisions, such as adjuvant therapies, timing of chemotherapy and abandoning ineffective therapies. If sensitivity of the tests could increase, CTCs might be useful for screening and early disease.
  
  
  OBJECTIVE
  To review clinical studies measuring CTCs in prostate and colorectal cancers, and to outline emerging CTC measurement techniques.
  
  
  METHODS
  A Medline review of selected 2007 - 2008 articles focusing on CTC measurement in prostate and colorectal cancers.
  
  
  CONCLUSIONS
  The CellSearch CTC test has been studied in several clinical settings and has shown useful sensitivity for advanced disease, and may become a surrogate marker for survival in advanced disease. At present, it is the only regulatory body-approved system for clinical CTC measurement in metastatic cancer. Reverse transcriptase polymerase chain reaction techniques have a longer history and have identified interesting markers, but are still used only in a research setting. Newer CTC detection methods have been reported that may increase sensitivity and allow testing in early disease.
authors.affiliation: The University of Texas, MD Anderson Cancer Center, Department of Urology, 1515 Holcombe Blvd, Unit 1373, Houston, TX 77030, USA +1 713 792 3250 ; +1 713 794 4824 ; Johndavis@mdanderson.org.
authors.forename: John W
authors.initials: JW
authors.lastname: Davis