title: A study of diffusion-weighted magnetic resonance imaging in men with untreated localised prostate cancer on active surveillance.
abstract: BACKGROUND
  Markers that predict the behaviour of localised prostate cancer are needed to identify patients that require treatment.
  
  
  OBJECTIVE
  We have analysed the apparent diffusion coefficient (ADC) generated from diffusion-weighted magnetic resonance imaging (DW-MRI) with respect to repeat biopsy findings and time to radical treatment in patients in a prospective study of active surveillance.
  
  
  METHODS
  Some 86 men recruited between 2002 and 2006 were followed for a median of 29 mo. Patients had clinical stage T1/T2a N0/Nx M0/Mx adenocarcinoma of the prostate, prostate-specific antigen (PSA) level<15 ng/ml, Gleason score≤7, primary Gleason grade≤3, and positive biopsy cores (pbc)≤50%.
  
  
  METHODS
  All patients had DW-MRI in addition to standard MRI sequences. Tumour regions of interest (ROIs) were identified using T2-weighted fast-spin echo images as focal areas of restricted diffusion. Univariate analyses including all clinical variables and tumour ADC data were performed with respect to repeat biopsy findings and time to radical treatment. Receiver operating curves (ROC) compared predictive variables.
  
  
  CONCLUSIONS
  Patients in the study had a median age of 66 yr and a median initial PSA level of 6.7 ng/ml. Some 39 patients (45%) received deferred radical treatment, and 34 patients (40%) had adverse histology on repeat biopsy. According to univariate analysis, tumour ADC was a significant predictor of both adverse repeat biopsy findings (p<0.0001; hazard ratio [HR]: 1.3; 95% confidence interval [CI]: 1.1-1.6), and time to radical treatment (p<0.0001; HR: 1.5; 95% CI: 1.2-1.8). ROC curves for ADC showed an area under the curve (AUC) of 0.7 for prediction of adverse repeat biopsy findings and an AUC of 0.83 for prediction of radical treatment.
  
  
  CONCLUSIONS
  In patients with low-risk, localised disease, tumour ADC on DW-MRI may be a useful marker of prostate cancer progression and may help to identify patients who stand to benefit from radical treatment. This possibility warrants further study.
authors.affiliation: Academic Unit of Radiotherapy and Oncology, Department of Radiology, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, Surrey, UK. Nicholas.Vanas@rmh.nhs.uk
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: van As
authors.forename: Nandita M
authors.initials: NM
authors.lastname: de Souza
authors.forename: Sophie F
authors.initials: SF
authors.lastname: Riches
authors.forename: Veronica A
authors.initials: VA
authors.lastname: Morgan
authors.forename: Sayid A
authors.initials: SA
authors.lastname: Sohaib
authors.forename: David P
authors.initials: DP
authors.lastname: Dearnaley
authors.forename: Chris C
authors.initials: CC
authors.lastname: Parker
mesh_terms: D000368:Aged; D001706:Biopsy / Q000706:statistics & numerical data; D038524:Diffusion Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000706:statistics & numerical data*; D018579:Patient Selection; D011159:Population Surveillance; D011237:Predictive Value of Tests; D015995:Prevalence; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D012372:ROC Curve; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology