title: Incidence and predictive factors of pain flare after spine stereotactic body radiation therapy: secondary analysis of phase 1/2 trials.
abstract: OBJECTIVE
  To perform a secondary analysis of institutional prospective spine stereotactic body radiation therapy (SBRT) trials to investigate posttreatment acute pain flare.
  
  
  METHODS
  Medical records for enrolled patients were reviewed. Study protocol included baseline and follow-up surveys with pain assessment by Brief Pain Inventory and documentation of pain medications. Patients were considered evaluable for pain flare if clinical note or follow-up survey was completed within 2 weeks of SBRT. Pain flare was defined as a clinical note indicating increased pain at the treated site or survey showing a 2-point increase in worst pain score, a 25% increase in analgesic intake, or the initiation of steroids. Binary logistic regression was used to determine predictive factors for pain flare occurrence.
  
  
  RESULTS
  Of the 210 enrolled patients, 195 (93%) were evaluable for pain flare, including 172 (88%) clinically, 135 (69%) by survey, and 112 (57%) by both methods. Of evaluable patients, 61 (31%) had undergone prior surgery, 57 (29%) had received prior radiation, and 34 (17%) took steroids during treatment, mostly for prior conditions. Pain flare was observed in 44 patients (23%). Median time to pain flare was 5 days (range, 0-20 days) after the start of treatment. On multivariate analysis, the only independent factor associated with pain flare was the number of treatment fractions (odds ratio = 0.66, P=.004). Age, sex, performance status, spine location, number of treated vertebrae, prior radiation, prior surgery, primary tumor histology, baseline pain score, and steroid use were not significant.
  
  
  CONCLUSIONS
  Acute pain flare after spine SBRT is a relatively common event, for which patients should be counseled. Additional study is needed to determine whether prophylactic or symptomatic intervention is preferred.
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Hubert Y
authors.initials: HY
authors.lastname: Pan
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Pamela K
authors.initials: PK
authors.lastname: Allen
authors.affiliation: Department of Symptom Research, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Xin S
authors.initials: XS
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas; Department of Radiation Oncology, USC Norris Cancer Center, Los Angeles, California.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Laurence D
authors.initials: LD
authors.lastname: Rhines
authors.affiliation: Department of Neurosurgery, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Claudio E
authors.initials: CE
authors.lastname: Tatsui
authors.affiliation: Department of Diagnostic Radiology, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Behrang
authors.initials: B
authors.lastname: Amini
authors.affiliation: Department of Radiation Physics, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Xin A
authors.initials: XA
authors.lastname: Wang
authors.affiliation: Department of Genitourinary Medical Oncology, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Nizar M
authors.initials: NM
authors.lastname: Tannir
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas. Electronic address: AJGhia@mdanderson.org.
authors.forename: Amol J
authors.initials: AJ
authors.lastname: Ghia
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000701:Analgesics, Opioid / Q000008:administration & dosage; D000704:Analysis of Variance; D003907:Dexamethasone / Q000008:administration & dosage; D019583:Dose Fractionation, Radiation; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy / Q000453:epidemiology* / Q000209:etiology; D016634:Radiosurgery / Q000009:adverse effects*; D013125:Spinal Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D005938:Glucocorticoids; D003907:Dexamethasone