title: Tumor lesion diameter on diffusion weighted magnetic resonance imaging could help predict insignificant prostate cancer in patients eligible for active surveillance: preliminary analysis.
abstract: OBJECTIVE
  We analyzed the pathological outcomes of candidates for active surveillance according to tumor lesion diameter on diffusion weighted magnetic resonance imaging.
  
  
  METHODS
  We retrospectively analyzed 188 candidates for active surveillance who had undergone diffusion weighted magnetic resonance imaging before radical prostatectomy between 2006 and 2012. We measured the diameter of the suspicious tumor lesion on diffusion weighted magnetic resonance imaging and stratified the cohort into 2 groups. Group 1 included patients with normal magnetic resonance imaging or a suspicious tumor lesion smaller than 1 cm and group 2 included patients with a suspicious tumor lesion larger than 1 cm. We compared pathological outcomes including insignificant prostate cancer in each group and analyzed whether different tumor diameters resulted in a change in insignificant prostate cancer rates.
  
  
  RESULTS
  Group 1 consisted of 115 (61.2%) patients and group 2 included 73 (38.8%) patients. In group 1 magnetic resonance imaging was normal in 72 patients. Mean ± SD diameter of suspicious tumor lesions was 12.0 ± 5.58 mm. Tumor volume was significantly different between the groups (0.73 ± 0.86 vs 1.09 ± 1.07 cm(3), p = 0.018), as was the rate of insignificant prostate cancer (48.7% vs 24.7%, p = 0.001). The rate of insignificant prostate cancer decreased as tumor diameter increased over 1 cm. On multivariate logistic regression analysis the diameter of suspicious tumor lesions was an important predictor of insignificant prostate cancer (OR 0.319, p = 0.014).
  
  
  CONCLUSIONS
  Our analysis demonstrates that the simple measurement of the diameter of suspicious tumor lesions on diffusion weighted magnetic resonance imaging could improve the prediction of insignificant prostate cancer in candidates for active surveillance.
authors.affiliation: Department of Urology, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Lee
authors.forename: Kyo Chul
authors.initials: KC
authors.lastname: Koo
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Lee
authors.forename: Koon Ho
authors.initials: KH
authors.lastname: Rha
authors.forename: Young Deuk
authors.initials: YD
authors.lastname: Choi
authors.forename: Sung Joon
authors.initials: SJ
authors.lastname: Hong
authors.forename: Byung Ha
authors.initials: BH
authors.lastname: Chung
mesh_terms: D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011237:Predictive Value of Tests; D011471:Prostatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D047368:Tumor Burden; D057832:Watchful Waiting
keywords: ADC; AS; DW-MRI; ECE; MRI; PRIAS; PSA; PSA density; PSAD; Prostate Cancer Research International: Active Surveillance; RP; SVI; active surveillance; apparent diffusion coefficient; diffusion magnetic resonance imaging; diffusion weighted magnetic resonance imaging; extracapsular extension; magnetic resonance imaging; prostate specific antigen; prostatic neoplasms; radical prostatectomy; seminal vesicle invasion; watchful waiting