title: Prostate-specific antigen density is predictive of outcome in suboptimal prostate seed brachytherapy.
abstract: In prostate seed brachytherapy, a D90of <130 Gy is an accepted predictive factor for biochemical failure (BF). We studied whether there is a subpopulation that does not need additional treatment after a suboptimal permanent seed brachytherapy implantation.
  
  
  
  A total of 486 patients who had either BF or a minimum followup of 48 months without BF were identified. BF was defined according to the Phoenix definition (nadir prostate-specific antigen + 2). Univariate and multivariate analyses were performed, adjusting for known prognostic factors such as D90and prostate-specific antigen density (PSAD) of ≥0.15 ng/mL/cm3, to evaluate their ability to predict BF.
  
  
  
  Median followup for patients without BF was 72 months (interquartile range 56-96). BF-free recurrence rate at 5 years was 95% and at 8 years 88%. In univariate analysis, PSAD and cancer of the prostate risk assessment score were predictive of BF. On multivariate analysis, none of the factors remained significant. The best prognosis had patients with a low PSAD (<0.15 ng/mL/cm3) and an optimal implant at 30 days after implantation (as defined by D90≥ 130 Gy) compared to patients with both factors unfavorable (p = 0.006). A favorable PSAD was associate with a good prognosis, independently of the D90(<130 Gy vs. ≥130 Gy, p = 0.7).
  
  
  
  Patients with a PSAD of <0.15 ng/mL/cm3have little risk of BF, even in the case of a suboptimal implant. These results need to be validated in other patients' cohorts.
authors.affiliation: Department of Radiation Oncology, Centre hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Quebec, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Benzaquen
authors.affiliation: Department of Radiation Oncology, Centre hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Quebec, Canada; CRCHUM-Centre de recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada.
authors.forename: Guila
authors.initials: G
authors.lastname: Delouya
authors.affiliation: Department of Radiation Oncology, Centre hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Quebec, Canada; CRCHUM-Centre de recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Ménard
authors.affiliation: Department of Radiation Oncology, Centre hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Quebec, Canada; CRCHUM-Centre de recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada.
authors.forename: Maroie
authors.initials: M
authors.lastname: Barkati
authors.affiliation: Department of Radiation Oncology, Centre hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Montréal, Quebec, Canada; CRCHUM-Centre de recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Quebec, Canada. Electronic address: daniel.taussky.chum@ssss.gouv.qc.ca.
authors.forename: Daniel
authors.initials: D
authors.lastname: Taussky
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D018572:Disease-Free Survival; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011237:Predictive Value of Tests; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D018570:Risk Assessment; D017211:Treatment Failure
chemical_list: D017430:Prostate-Specific Antigen
keywords: Brachytherapy; PSA density; Prostate cancer; Risk biochemical failure