title: Endoscopic gold fiducial marker placement into the bladder wall to optimize radiotherapy targeting for bladder-preserving management of muscle-invasive bladder cancer: feasibility and initial outcomes.
abstract: OBJECTIVE
  Bladder radiotherapy is a management option for carefully selected patients with muscle-invasive bladder cancer. However, the inability to visualize the tumor site during treatment and normal bladder movement limits targeting accuracy and increases collateral radiation. A means to accurately and reliably target the bladder during radiotherapy is needed.
  
  
  METHODS
  Eighteen consecutive patients with muscle-invasive bladder cancer (T1-T4) elected bladder-preserving treatment with maximal transurethral resection (TUR), radiation and concurrent chemotherapy. All underwent endoscopic placement of 24-K gold fiducial markers modified with micro-tines (70 [2.9×0.9 mm.]; 19 [2.1×0.7 mm.) into healthy submucosa 5-10 mm. from the resection margin, using custom-made coaxial needles. Marker migration was assessed for with intra-op bladder-filling cystogram and measurement of distance between markers. Set-up error and marker retention through completion of radiotherapy was confirmed by on-table portal imaging.
  
  
  RESULTS
  Between 1/2007 and 7/2012, a total of 89 markers (3-5 per tumor site) were placed into 18 patients of mean age 73.6 years. Two patients elected cystectomy before starting treatment; 16/18 completed chemo-radiotherapy. All (100%) markers were visible with all on-table (portal, cone-beam CT), fluoroscopy, plain-film, and CT-scan imaging. In two patients, 1 of 4 markers placed at the tumor site fell-out (voided) during the second half of radiotherapy. All other markers (80/82, 98%) were present through the end of radio-therapy. No intraoperative (e.g. uncontrolled bleeding, collateral injury) or post-operative complications (e.g. stone formation, urinary tract infection, post-TUR hematuria >48 hours) occurred. Use of micro-tined fiducial tumor-site markers afforded a 2 to 6-fold reduction in bladder-area targeted with high-dose radiation.
  
  
  CONCLUSIONS
  Placement of the micro-tined fiducial markers into the bladder was feasible and associated with excellent retention-rate and no complications. All markers were well-visualized during radiotherapy with all imaging modalities. Bladder fiducial markers improve targeting accuracy, and may increase treatment efficacy and reduce morbidity from collateral radiation.
authors.affiliation: Department of Urology, University of California San Francisco, San Francisco, California, United States of America; University of California San Francisco - Helen Diller Family Comprehensive Cancer Center, San Francisco, California, United States of America.
authors.forename: Maurice M
authors.initials: MM
authors.lastname: Garcia
authors.affiliation: Department of Radiation Oncology, University of California San Francisco, San Francisco, California, United States of America; University of California San Francisco - Helen Diller Family Comprehensive Cancer Center, San Francisco, California, United States of America.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Gottschalk
authors.affiliation: Department of Urology, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Brajtbord
authors.affiliation: Department of Urology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Badrinath R
authors.initials: BR
authors.lastname: Konety
authors.affiliation: Department of Urology, University of California San Francisco, San Francisco, California, United States of America; University of California San Francisco - Helen Diller Family Comprehensive Cancer Center, San Francisco, California, United States of America.
authors.forename: Maxwell V
authors.initials: MV
authors.lastname: Meng
authors.affiliation: Department of Urology, University of California San Francisco, San Francisco, California, United States of America; Department of Radiation Oncology, University of California San Francisco, San Francisco, California, United States of America; University of California San Francisco - Helen Diller Family Comprehensive Cancer Center, San Francisco, California, United States of America.
authors.forename: Mack
authors.initials: M
authors.lastname: Roach
authors.affiliation: Department of Urology, University of California San Francisco, San Francisco, California, United States of America; University of California San Francisco - Helen Diller Family Comprehensive Cancer Center, San Francisco, California, United States of America.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Carroll
mesh_terms: D040421:Cell Phone; D004724:Endoscopy; D005240:Feasibility Studies; D006801:Humans; D009132:Muscles / Q000473:pathology*; D009361:Neoplasm Invasiveness; D001749:Urinary Bladder Neoplasms / Q000473:pathology / Q000532:radiotherapy*