title: External validation of risk classification in patients with docetaxel-treated castration-resistant prostate cancer.
abstract: BACKGROUND
  Castration-resistant prostate cancer (CRPC) patients have poor prognoses, and docetaxel (DTX) is among the few treatment options. An accurate risk classification to identify CRPC patient groups for which DTX would be effective is urgently warranted. The Armstrong risk classification (ARC), which classifies CRPC patients into 3 groups, is superior; however, its usefulness remains unclear, and further external validation is required before clinical use. This study aimed to examine the clinical significance of the ARC through external validation in DTX-treated Japanese CRPC patients.
  
  
  METHODS
  CRPC patients who received 2 or more DTX cycles were selected for this study. Patients were classified into good-, intermediate-, and poor-risk groups according to the ARC. Prostate-specific antigen (PSA) responses and overall survival (OS) were calculated and compared between the risk groups. A multivariate analysis was performed to clarify the relationship between the ARC and major patient characteristics.
  
  
  RESULTS
  Seventy-eight CRPC patients met the inclusion criteria. Median PSA levels at DTX initiation was 20 ng/mL. Good-, intermediate-, and poor-risk groups comprised 51 (65%), 17 (22%), and 10 (13%) patients, respectively. PSA response rates ≥ 30% and ≥ 50% were 33%, 41%, and 30%, and 18%, 41%, and 20% in the good-, intermediate-, and poor-risk groups, respectivcixely, with no significant differences (p = 0.133 and 0.797, respectively). The median OS in the good-, intermediate-, and poor-risk groups were statistically significant (p < 0.001) at 30.1, 14.2, and 5.7 months, respectively. A multivariate analysis revealed that the ARC and PSA doubling time were independent prognostic factors.
  
  
  CONCLUSIONS
  Most of CRPC patients were classified into good-risk group according to the ARC and the ARC could predict prognosis in DTX-treated CRPC patients.
  
  
  BACKGROUND
  University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) number, UMIN000011969.
authors.affiliation: Department of Urology, Jichi Medical University, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498, Japan. nknkzhk@jichi.ac.jp.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakano
authors.forename: Kenji
authors.initials: K
authors.lastname: Komatsu
authors.forename: Taro
authors.initials: T
authors.lastname: Kubo
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Natsui
authors.forename: Akinori
authors.initials: A
authors.lastname: Nukui
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Kurokawa
authors.forename: Minoru
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Morita
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood; D000077143:Docetaxel; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000145:classification / Q000175:diagnosis* / Q000188:drug therapy*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012680:Sensitivity and Specificity; D043823:Taxoids / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D043823:Taxoids; D000077143:Docetaxel; D017430:Prostate-Specific Antigen
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