title: High-dose-rate brachytherapy boost to the dominant intra-prostatic tumor region: hemi-irradiation of prostate cancer.
abstract: BACKGROUND
  To assess the feasibility, toxicity, and outcome of prostate hemi-irradiation with a high-dose-rate brachytherapy (HDR-BT) boost for patients presumed to harbor dominant intra-prostatic tumors in a single lobe.
  
  
  METHODS
  After 3D conformal external radiotherapy (3DCRT) to 64-64.4 Gy, 77 patients with non-metastatic locally aggressive prostate cancer have been treated from 2000 to 2004, with HDR-BT using temporary open MRI-guided (192) Ir implants, to escalate the dose in the boost region. Twenty patients (26%) had one lobe involvement (i.e., one sided endorectal MRI, rectal examination, and biopsies) and were boosted to one side of the gland only. A dose of 12, 14, and 16 Gy in two fractions was delivered to 5, 6, and 9 patients, respectively.
  
  
  RESULTS
  After a median follow-up 69 months, no differences in late rectal toxicity were observed between the unilaterally and bilaterally irradiated cohorts. Although, grade 2 late urinary toxicity was worse in the hemi-irradiated group (P = 0.03), severe grade ≥3 late urinary toxicity at 5 years was not different: 10% versus 8.8% in the unilaterally and bilaterally irradiated cohorts, respectively. Grade 4 late urinary toxicity, however, was exclusively observed in patients boosted to both lobes (5/57, 8.8%). Five-year biochemical relapse-free survival was 79.7% versus 70.5% for the unilateral and bilateral boost groups, respectively (P = 0.99).
  
  
  CONCLUSIONS
  Prostate hemi-irradiation with a HDR-BT boost to the dominant tumor region may be considered when rectal examination, MRI, and biopsies suggest one lobe involvement. Nevertheless, strict dosimetric optimization is needed in order to further reduce the risk of late severe toxicity.
authors.affiliation: Department of Radiation Oncology, University Hospital of Geneva, Geneva, Switzerland.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schick
authors.forename: Youri
authors.initials: Y
authors.lastname: Popowski
authors.forename: Philippe
authors.initials: P
authors.lastname: Nouet
authors.forename: Sabine
authors.initials: S
authors.lastname: Bieri
authors.forename: Michel
authors.initials: M
authors.lastname: Rouzaud
authors.forename: Haleem
authors.initials: H
authors.lastname: Khan
authors.forename: Damien Charles
authors.initials: DC
authors.lastname: Weber
authors.forename: Raymond
authors.initials: R
authors.lastname: Miralbell
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D015331:Cohort Studies; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D005500:Follow-Up Studies; D041981:Gastrointestinal Tract / Q000528:radiation effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000528:radiation effects*; D011471:Prostatic Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D015996:Survival Rate; D013997:Time Factors; D017211:Treatment Failure; D014566:Urogenital System / Q000528:radiation effects