title: Circulating tumor cells as a biomarker predictive of sensitivity to docetaxel chemotherapy in patients with castration-resistant prostate cancer.
abstract: OBJECTIVE
  We examined whether Circulating Tumor Cells (CTCs) can be used to predict survival in patients with bone-metastatic castration-resistant-prostate cancer (mCRPC) treated with docetaxel chemotherapy.
  
  
  METHODS
  All patients with mCRPC who had experienced treatment failure with androgen deprivation therapy and had received docetaxel chemotherapy were eligible for study inclusion. CTCs in whole blood were enumerated with the CellSearch System.
  
  
  RESULTS
  The median CTC count at baseline before starting trial treatment was 7 (range=0-227) CTCs per 7.5 ml blood. Out of the 57 patients, 24 (42.1%) had a CTC count of less than 5, while 27 patients (47.4%) had a CTC count of 5-50 and six patients (10.5%) had a CTC count of more than 50. A threshold of 5 or more CTCs per 7.5 ml blood was used to assess the ability to predict survival. The patient charts were examined to determine the median overall survival time, which ranged from 6 to 37 months (mean=12.8±8.1 months, median=15.3 months). Thirty-three patients (57.9%) had 5 or more CTCs before docetaxel chemotherapy, with a median overall survival of 10.5 months compared to 25.0 months for 24 patients (42.1%) with fewer than 5 CTCs (p<0.001). CTC and alkaline phosphatase (ALP) were independent predictors of overall survival time (p=0.004, and p=0.023, respectively). In addition, poorer overall survival was predicted by a CTC count of 5 or more after three courses of docetaxel chemotherapy.
  
  
  CONCLUSIONS
  The CTC count may be an independent predictor of overall survival in patients with mCRPC treated with docetaxel chemotherapy. The numbers of CTCs detected was important in assessing response to chemotherapy and predict disease outcome.
authors.affiliation: Department of Urology, The University of Kyorin, Mitaka, Tokyo, Japan toke@ks.kyorin-u.ac.jp.
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Okegawa
authors.affiliation: Department of Urology, The University of Kyorin, Mitaka, Tokyo, Japan.
authors.forename: Naoshi
authors.initials: N
authors.lastname: Itaya
authors.affiliation: Department of Urology, The University of Kyorin, Mitaka, Tokyo, Japan.
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Hara
authors.affiliation: Department of Urology, The University of Kyorin, Mitaka, Tokyo, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Tambo
authors.affiliation: Department of Urology, The University of Kyorin, Mitaka, Tokyo, Japan.
authors.forename: Kikuo
authors.initials: K
authors.lastname: Nutahara
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000097:blood*; D001859:Bone Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000401:mortality / Q000556:secondary; D018450:Disease Progression; D000077143:Docetaxel; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D011446:Prospective Studies; D064129:Prostatic Neoplasms, Castration-Resistant / Q000097:blood* / Q000188:drug therapy / Q000401:mortality / Q000473:pathology; D012680:Sensitivity and Specificity; D015996:Survival Rate; D043823:Taxoids / Q000627:therapeutic use*
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D043823:Taxoids; D000077143:Docetaxel
keywords: Circulating tumor cells; biomarker; castration-resistant prostate cancer; docetaxel