title: Stereotactic body radiotherapy with a focal boost to the MRI-visible tumor as monotherapy for low- and intermediate-risk prostate cancer: early results.
abstract: BACKGROUND
  There is growing evidence that prostate cancer (PC) cells are more sensitive to high fraction dose in hypofractionation schemes. High-dose-rate (HDR) brachytherapy as monotherapy is established to be a good treatment option for PC using extremely hypofractionated schemes. This hypofractionation can also be achieved with stereotactic body radiotherapy (SBRT). We report results on toxicity, PSA response, and quality of life (QOL) in patients treated with SBRT for favorable-risk PC.
  
  
  METHODS
  Over the last 4 years, 50 hormone-naïve patients with low- and intermediate-risk PC were treated with SBRT to a total dose of 38 Gy delivered in four daily fractions of 9.5 Gy. An integrated boost to 11 Gy per fraction was applied to the dominant lesion if visible on MRI. Toxicity and QoL was assessed prospectively using validated questionnaires.
  
  
  RESULTS
  Median follow-up was 23 months. The 2-year actuarial biochemical control rate was 100%. Median PSA nadir was 0.6 ng/ml. Median International Prostate Symptoms Score (IPSS) was 9/35 before treatment, with a median increase of 4 at 3 months and remaining stable at 13/35 thereafter. The EORTC/RTOG toxicity scales showed grade 2 and 3 gastrointestinal (GI) acute toxicity in 12% and 2%, respectively. The late grade 2 GI toxicity was 3% during 24 months FU. Genitourinary (GU) grade 2, 3 toxicity was seen in 15%, 8%, in the acute phase and 10%, 6% at 24 months, respectively. The urinary, bowel and sexual domains of the EORTC-PR25 scales recovered over time, showing no significant changes at 24 months post-treatment.
  
  
  CONCLUSIONS
  SBRT to 38 Gy in 4 daily fractions for low- and intermediate-risk PC patients is feasible with low acute and late genitourinary and gastrointestinal toxicity. Longer follow-up preferably within randomized studies, is required to compare these results with standard fractionation schemes.
authors.affiliation: Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Groene Hilledijk, Rotterdam, The Netherlands. s.aluwini@erasmusmc.nl
authors.forename: Shafak
authors.initials: S
authors.lastname: Aluwini
authors.forename: Peter
authors.initials: P
authors.lastname: van Rooij
authors.forename: Mischa
authors.initials: M
authors.lastname: Hoogeman
authors.forename: Wim
authors.initials: W
authors.lastname: Kirkels
authors.forename: Inger-Karine
authors.initials: IK
authors.lastname: Kolkman-Deurloo
authors.forename: Chris
authors.initials: C
authors.lastname: Bangma
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D011788:Quality of Life; D011874:Radiometry; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods*