title: Quantification of skeletal metastases in castrate-resistant prostate cancer predicts progression-free and overall survival.
abstract: OBJECTIVE
  To report a simplified and effective method for substratification of M1 castrate-resistant prostate cancer (CRPC) by correlating progression-free (PFS) and overall survival (OS) with simple quantification of skeletal metastases.
  
  
  METHODS
  In all, 561 men with M1 CRPC were studied longitudinally. Individual bone scan disease burden, quantified by counting bone metastasis number, was correlated with clinical outcome using specific threshold points of 1-4, 5-20 and >20 detectable lesions.
  
  
  RESULTS
  Patients with a higher metastasis number had a shorter PFS and OS (hazard ratio [HR] 2.0, 95% confidence interval [CI] 1.7-2.4; P < 0.001). Patients with 1-4 metastases had much better PFS and OS than those with 5-20 metastases. The median PFS and OS in the latter was 10.9 (95% CI 8.4-12.8) and 22.1 (95% CI: 18.5-24.5) months, respectively. PFS and OS for patients with >20 metastases were shorter still [median 5.3 (95% CI 3.4-6.9) months and 13.3 (95% CI 11.3-17.6) months, respectively]. Dichotomising into cohorts with 1-4 and ≥5 metastases, the latter group had considerably poorer PFS [8.4 (95% CI 6.8-10.3) months; P < 0.001) and OS [18.7 (95% CI 17.5-22.1) months; P < 0.001].
  
  
  CONCLUSIONS
  Dichotomising patients with CRPC into cohorts with 1-4 or ≥5 skeletal metastases identifies a better and a worse cohort in a manner that is easy and clinically accessible. This simple method facilitates disease stratification and patient management, enabling clinicians to counsel patients more effectively about long-term outcomes and to help select intervention therapies more effectively.
authors.affiliation: Department of Urology, The Christie NHS Foundation Trust, Manchester, UK.|Department of Urology, Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: Campbell
authors.initials: C
authors.lastname: Tait
authors.affiliation: Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK.
authors.forename: David
authors.initials: D
authors.lastname: Moore
authors.affiliation: Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Hodgson
authors.affiliation: The Genito Urinary Cancer Research Group, Institute of Cancer Sciences, University of Manchester, Manchester, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Brown
authors.affiliation: AstraZeneca, Macclesfield, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Morris
authors.affiliation: AstraZeneca, Macclesfield, UK.
authors.forename: Jim
authors.initials: J
authors.lastname: Growcott
authors.affiliation: AstraZeneca, Macclesfield, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Malone
authors.affiliation: AstraZeneca, Macclesfield, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hughes
authors.affiliation: Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Renehan
authors.affiliation: Department of Urology, The Christie NHS Foundation Trust, Manchester, UK.|Department of Urology, Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: Noel W
authors.initials: NW
authors.lastname: Clarke
authors.affiliation: Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Dive
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000556:secondary*; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D064129:Prostatic Neoplasms, Castration-Resistant / Q000401:mortality / Q000473:pathology*; D011877:Radionuclide Imaging; D015996:Survival Rate
keywords: CRPC; bone scintigraphy; metastasis; prostate cancer; survival