title: Prediction model for recurrence probabilities after intravesical chemotherapy in patients with intermediate-risk non-muscle-invasive bladder cancer, including external validation.
abstract: OBJECTIVE
  To develop a model to predict recurrence for patients with intermediate-risk (IR) non-muscle-invasive bladder cancer (NMIBC) treated with intravesical chemotherapy which can be challenging because of the heterogeneous characteristics of these patients.
  
  
  METHODS
  Data from three Dutch trials were combined. Patients treated with intravesical chemotherapy with characteristics according to the IR definition of the EAU guideline 2013 were included. Uni- and multivariable Cox regression with selection methods were used to identify predictors of recurrence at 1, 2, and 5 years. An easy-readable table for recurrence probabilities was developed. An external validation was done using data from Spanish patients.
  
  
  RESULTS
  A total of 724 patients were available for analyses, of which 305 were primary patients. Recurrences occurred in 413 patients (57%). History of recurrences, history of intravesical treatment, grade 2, multiple tumors, and adjuvant treatment with epirubicin were relevant predictors for recurrence-free survival with hazard ratios of 1.48, 1.38, 1.22, 1.56, and 1.27, respectively. A table for recurrence probabilities was developed using these five predictors. Based on the probability of recurrence, three risk groups were identified. Patients in each of the separate risk groups should be scheduled for less or more aggressive treatment. The model showed sufficient discrimination and good predictive accuracy. External validation showed good validity.
  
  
  CONCLUSIONS
  In our model, we identified five relevant predictors for recurrence-free survival in IR-NMIBC patients treated with intravesical chemotherapy. These recurrence predictors allow the urologists to stratify patients in risk groups for recurrence that could help in deciding for an individualized treatment approach.
authors.affiliation: Department of Urology, Radboud University Medical Centre, Geert Grooteplein Zuid 10 (659), P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. rianne_lammers@hotmail.com.
authors.forename: Rianne J M
authors.initials: RJ
authors.lastname: Lammers
authors.affiliation: Department for Health Evidence, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Jan C M
authors.initials: JC
authors.lastname: Hendriks
authors.affiliation: Fundacio Puigvert, Oncology Urology, Barcelona, Spain.
authors.forename: O Rodriguez Faba
authors.initials: OR
authors.lastname: Rodriguez Faba
authors.affiliation: Department of Urology, Radboud University Medical Centre, Geert Grooteplein Zuid 10 (659), P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.|CuraTrial SMO & Research, Arnhem, The Netherlands.
authors.forename: Wim P J
authors.initials: WP
authors.lastname: Witjes
authors.affiliation: Fundacio Puigvert, Oncology Urology, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Palou
authors.affiliation: Department of Urology, Radboud University Medical Centre, Geert Grooteplein Zuid 10 (659), P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. Fred.Witjes@radboudumc.nl.
authors.forename: J Alfred
authors.initials: JA
authors.lastname: Witjes
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000283:Administration, Intravesical; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D011379:Prognosis; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis / Q000188:drug therapy*
chemical_list: D000276:Adjuvants, Immunologic
keywords: Adjuvant chemotherapy; Intravesical administration; Prediction model; Recurrence; Urinary bladder neoplasm