title: Stereotactic ablative radiotherapy with CyberKnife in the treatment of locally advanced prostate cancer: preliminary results.
abstract: OBJECTIVE
  Recent clinical reports of stereotactic ablative radiotherapy (SABR) in the treatment of low-risk prostate cancer have been encouraging. Our study evaluates the efficacy and safety of SABR using the CyberKnife system for treating intermediate- to very-high-risk prostate cancer.
  
  
  METHODS
  Between May 2010 and June 2013, 31 patients (15 intermediate risk, 14 high risk, and 2 very high risk) without pelvic lymph node metastasis were enrolled retrospectively. The treatment consisted of 37.5 Gy in 5 fractions over 1-2 weeks using CyberKnife SABR. Twenty-five patients (81%) received androgen deprivation therapy (ADT). Biochemical failure was defined using the nadir + 2 criterion. Toxicity was assessed with the Common Terminology Criteria of Adverse Events (version 4).
  
  
  RESULTS
  The median follow-up was 36 months (range 7-58 months). The median pretreatment prostate--pecific antigen (PSA) was 13.5 ng/mL (range 4.5-124.0 ng/mL). The median PSA decreased to 0.09 ng/mL (range &lt;0.04-5.38 ng/mL) and 0.12 ng/mL (range &lt;0.04-2.63 ng/mL) at 6 months and 12 months after SABR, respectively. The 3-year biochemical relapse-free survival was 90.2% for all patients, 100% for the intermediate-risk patients, and 82% for the high- and very-high-risk patients (p = 0.186). No patient experienced ≥ grade 3 toxicity. There were 7 acute and 5 late grade 2 genitourinary toxicities and 1 acute and no late grade 2 gastrointestinal toxicity.
  
  
  CONCLUSIONS
  Our preliminary results support that CyberKnife SABR with ADT is safe and feasible in patients with intermediate- to high-risk prostate cancer. A further large-scale clinical trial with longer follow-up is warranted.
authors.affiliation: Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan - ROC.
authors.forename: Chao-Yueh
authors.initials: CY
authors.lastname: Fan
authors.affiliation: Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan - ROC.
authors.forename: Hsing-Lung
authors.initials: HL
authors.lastname: Chao
authors.affiliation: Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan - ROC.
authors.forename: Wen-Yen
authors.initials: WY
authors.lastname: Huang
authors.affiliation: Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan - ROC.
authors.forename: Chun-Shu
authors.initials: CS
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan - ROC.
authors.forename: Chang-Ming
authors.initials: CM
authors.lastname: Chen
authors.affiliation: Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan - ROC.
authors.forename: Cheng-Hsiang
authors.initials: CH
authors.lastname: Lo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology* / Q000601:surgery*; D016634:Radiosurgery; D012008:Recurrence; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen