title: The effect of loose versus stranded seeds on biochemical no evidence of disease in patients with carcinoma of the prostate treated with iodine-125 brachytherapy.
abstract: OBJECTIVE
  The British Columbia Cancer Agency has been performing iodine-125 prostate brachytherapy since 1998, initially using loose seeds and phasing into the exclusive use of RAPIDStrand (RS) (Oncura Inc., Plymouth Meeting, PA) by November 2000. The aim of this study was to investigate rates of biochemical no evidence of disease (bNED) in patients treated with loose seeds compared with RS from this population-based cohort.
  
  
  METHODS
  Between July 1998 and February 2006, 1500 implants were performed (327 loose and 1173 RS). Biochemical failure is reported using the Phoenix definition and prostate-specific antigen (PSA) >0.4ng/mL at ≥48 months postimplant. Actuarial estimates were calculated by the Kaplan-Meier method. Analysis was repeated with the first 100 loose and stranded implants excluded to assess the learning curve effect. Log-rank test was used to evaluate differences in bNED. Variables showing association with bNED were included in a multivariate model.
  
  
  RESULTS
  There was no difference between loose and stranded seeds. Estimated rate of bNED was 93.5% (95% confidence interval [CI], 90.6-96.4) at 7 years for patients treated with loose seeds and 94.0% (95% CI, 91.8-96.2) for patients treated with RS according to Phoenix definition (p=0.846). Using the PSA >0.4ng/mL definition, estimated rates were 91.3% (95% CI, 88.0-94.6) and 91.9% (95% CI, 89.7-94.1) for loose and stranded seeds, respectively (p=0.871). Exclusion of the first 100 loose and stranded implants also revealed no difference in bNED.
  
  
  CONCLUSIONS
  This study of 1500 patients treated with iodine-125 brachytherapy demonstrates no difference in bNED between loose and stranded seeds, using either Phoenix or PSA >0.4ng/mL definitions of biochemical failure.
authors.affiliation: Department of Radiation Oncology, BC Cancer Agency, Vancouver, British Columbia, Canada. cherbert@bccancer.bc.ca
authors.forename: Christopher
authors.initials: C
authors.lastname: Herbert
authors.forename: W James
authors.initials: WJ
authors.lastname: Morris
authors.forename: Jeremy
authors.initials: J
authors.lastname: Hamm
authors.forename: Vincent
authors.initials: V
authors.lastname: Lapointe
authors.forename: Michael
authors.initials: M
authors.lastname: McKenzie
authors.forename: Tom
authors.initials: T
authors.lastname: Pickles
authors.forename: Ingrid
authors.initials: I
authors.lastname: Spadinger
authors.forename: Mira
authors.initials: M
authors.lastname: Keyes
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012008:Recurrence; D018570:Risk Assessment; D047368:Tumor Burden / Q000528:radiation effects
chemical_list: D007457:Iodine Radioisotopes