title: Brachytherapy improves biochemical failure-free survival in low- and intermediate-risk prostate cancer compared with conventionally fractionated external beam radiation therapy: a propensity score matched analysis.
abstract: OBJECTIVE
  To compare, in a retrospective study, biochemical failure-free survival (bFFS) and overall survival (OS) in low-risk and intermediate-risk prostate cancer patients who received brachytherapy (BT) (either low-dose-rate brachytherapy [LDR-BT] or high-dose-rate brachytherapy with external beam radiation therapy [HDR-BT+EBRT]) versus external beam radiation therapy (EBRT) alone.
  
  
  METHODS
  Patient data were obtained from the ProCaRS database, which contains 7974 prostate cancer patients treated with primary radiation therapy at four Canadian cancer institutions from 1994 to 2010. Propensity score matching was used to obtain the following 3 matched cohorts with balanced baseline prognostic factors: (1) low-risk LDR-BT versus EBRT; (2) intermediate-risk LDR-BT versus EBRT; and (3) intermediate-risk HDR-BT+EBRT versus EBRT. Kaplan-Meier survival analysis was performed to compare differences in bFFS (primary endpoint) and OS in the 3 matched groups.
  
  
  RESULTS
  Propensity score matching created acceptable balance in the baseline prognostic factors in all matches. Final matches included 2 1:1 matches in the intermediate-risk cohorts, LDR-BT versus EBRT (total n=254) and HDR-BT+EBRT versus EBRT (total n=388), and one 4:1 match in the low-risk cohort (LDR-BT:EBRT, total n=400). Median follow-up ranged from 2.7 to 7.3 years for the 3 matched cohorts. Kaplan-Meier survival analysis showed that all BT treatment options were associated with statistically significant improvements in bFFS when compared with EBRT in all cohorts (intermediate-risk EBRT vs LDR-BT hazard ratio [HR] 4.58, P=.001; intermediate-risk EBRT vs HDR-BT+EBRT HR 2.08, P=.007; low-risk EBRT vs LDR-BT HR 2.90, P=.004). No significant difference in OS was found in all comparisons (intermediate-risk EBRT vs LDR-BT HR 1.27, P=.687; intermediate-risk EBRT vs HDR-BT+EBRT HR 1.55, P=.470; low-risk LDR-BT vs EBRT HR 1.41, P=.500).
  
  
  CONCLUSIONS
  Propensity score matched analysis showed that BT options led to statistically significant improvements in bFFS in low- and intermediate-risk prostate cancer patient populations.
authors.affiliation: University of Western Ontario, London, Ontario, Canada.
authors.forename: Graham D
authors.initials: GD
authors.lastname: Smith
authors.affiliation: Department of Radiation Oncology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Pickles
authors.affiliation: Department of Radiation Oncology, Kelowna General Hospital, Kelowna, British Columbia, Canada.
authors.forename: Juanita
authors.initials: J
authors.lastname: Crook
authors.affiliation: Department of Radiation Oncology, L'Hotel Dieu de Quebec, Quebec City, Quebec, Canada.
authors.forename: Andre-Guy
authors.initials: AG
authors.lastname: Martin
authors.affiliation: Department of Radiation Oncology, L'Hotel Dieu de Quebec, Quebec City, Quebec, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Vigneault
authors.affiliation: Department of Radiation Oncology, Montreal General Hospital, Montreal, Quebec, Canada.
authors.forename: Fabio L
authors.initials: FL
authors.lastname: Cury
authors.affiliation: Department of Radiation Oncology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada.
authors.forename: Jim
authors.initials: J
authors.lastname: Morris
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Catton
authors.affiliation: Department of Radiation Oncology, Juravinski Cancer Centre, Hamilton, Ontario, Canada.
authors.forename: Himu
authors.initials: H
authors.lastname: Lukka
authors.affiliation: Department of Radiation Oncology, London Health Sciences Center, London, Ontario, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Warner
authors.affiliation: University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.affiliation: University of Western Ontario, London, Ontario, Canada; Department of Radiation Oncology, London Health Sciences Center, London, Ontario, Canada. Electronic address: George.Rodrigues@lhsc.on.ca.
authors.forename: George
authors.initials: G
authors.lastname: Rodrigues
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D002170:Canada; D015331:Cohort Studies; D018572:Disease-Free Survival; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D057216:Propensity Score; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012044:Regression Analysis; D012189:Retrospective Studies; D012306:Risk
chemical_list: D017430:Prostate-Specific Antigen