title: Semicontinuous low-dose-rate teletherapy for the treatment of recurrent glial brain tumors: final report of a phase I/II study.
abstract: OBJECTIVE
  Semicontinuous low-dose-rate teletherapy (SLDR) is a novel irradiation strategy that exploits the increased radiosensitivity of glial cells in a narrow range of reduced dose rate. We present the final report of a prospective Phase I/II study testing the feasibility of SLDR for the treatment of recurrent gliomas.
  
  
  METHODS
  Patients with previously irradiated recurrent gliomas were enrolled from November 1993 to March 1998. Patients received SLDR, delivered 6 to 8 hours/day at a dose rate of 40 to 50 cGy/hour for a total dose of 30 to 35 Gy given over 12 days using a modified cobalt-60 treatment unit. Acute central nervous system toxicity after SLDR treatment was the primary endpoint. Overall survival was a secondary endpoint.
  
  
  RESULTS
  Twenty patients were enrolled (14 World Health Organization Grade 4 glioma, 5 Grade 2 glioma, 1 ependymoma). No patients developed ≥ Grade 3 central nervous system toxicity at 3 months without radiographic evidence of tumor progression. Overall survival after SLDR was 56% at 6 months, 28% at 12 months, and 17% at 24 months. One patient survived >48 months, and 1 patient survived >60 months after SLDR treatment. Re-resection before SLDR treatment significantly improved 1-year overall survival for all patients and patients with Grade 4 glioma.
  
  
  CONCLUSIONS
  The delivery of SLDR is feasible in patients with recurrent gliomas and resulted in improved outcomes for patients who underwent re-resection. There were 2 long-term survivors (>48 months). This pilot study supports the notion that reduced dose rate influences the efficacy and tolerance of reirradiation in the treatment of recurrent gliomas.
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Malika L
authors.initials: ML
authors.lastname: Siker
authors.forename: Selim Y
authors.initials: SY
authors.lastname: Firat
authors.forename: Wade
authors.initials: W
authors.lastname: Mueller
authors.forename: Hendrikus
authors.initials: H
authors.lastname: Krouwer
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Schultz
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D004806:Ependymoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D005240:Feasibility Studies; D005910:Glioma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011446:Prospective Studies; D011832:Radiation Injuries / Q000473:pathology; D011878:Radiotherapy / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D016879:Salvage Therapy / Q000379:methods; D055815:Young Adult
chemical_list: D003037:Cobalt Radioisotopes