title: Delivering a third course of radiation to spine metastases using image-guided, intensity-modulated radiation therapy.
abstract: OBJECTIVE
  The objective of this study was to investigate the feasibility and safety of delivering a third course of radiation to patients with multiply recurrent metastatic disease to the spine.
  
  
  METHODS
  Between 2009 and 2011, 10 patients received a third course of radiation to spinal metastases at Memorial Sloan-Kettering Cancer Center using image-guided intensity-modulated radiation therapy (IMRT). Patient and tumor characteristics, dosimetry details, and outcomes were obtained using retrospective chart review. Spinal imaging was performed prior to treatment and at regular follow-up intervals. The cumulative biologically effective dose (BED) to the spinal cord and cauda equina was calculated and was normalized to 2 Gy equivalents (Gy(2/2)). Toxicity and local control were assessed.
  
  
  RESULTS
  The median time between the first and second courses of radiation was 18.5 months and the median time between the second and third courses was 11.5 months. The median follow-up from the third course of radiation was 12 months and the median overall survival was 13 months. Pain or neurological symptoms were improved in 80% of patients. The median spinal cord maximum dose normalized BED (nBED) for the whole cohort was 70.73 Gy(2/2) (range 51.9-101.7 Gy(2/2)). The median dose to 5% of the spinal cord D(05) nBED for the entire cohort was 59.4 Gy(2/2). Acute toxicity was most commonly fatigue and dermatitis, with 1 patient experiencing Grade 3 fatigue and 1 patient Grade 3 dermatitis. Late toxicity was limited to 2 cases of Grade 1 dysphagia. There was 1 case of Grade 1 neuropathy and 1 case of Grade 2 neuropathy. The crude rate of local control was 80% with 1 in-field failure and 1 marginal failure.
  
  
  CONCLUSIONS
  In this cohort of patients, a third course of IMRT to the spine was well tolerated with no significant late toxicities. Used as salvage therapy for select patients, a third course of radiation is a safe and effective treatment strategy.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan–Kettering Cancer Center, New York, NY 10065, USA. ekatsoul@gmail.com
authors.forename: Evangelia
authors.initials: E
authors.lastname: Katsoulakis
authors.forename: Nadeem
authors.initials: N
authors.lastname: Riaz
authors.forename: Brett
authors.initials: B
authors.lastname: Cox
authors.forename: James
authors.initials: J
authors.lastname: Mechalakos
authors.forename: Joan
authors.initials: J
authors.lastname: Zatcky
authors.forename: Mark
authors.initials: M
authors.lastname: Bilsky
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Yamada
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D016879:Salvage Therapy; D013125:Spinal Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000556:secondary; D015996:Survival Rate; D016896:Treatment Outcome