title: Pseudoprogression of low-grade gliomas after radiotherapy.
abstract: BACKGROUND
  Increasing mass effect following radiation therapy (RT) in patients with low-grade gliomas (LGGs) can be mistaken for tumor progression and/or malignant degeneration. Distinguishing pseudoprogression (PP) from true progression is crucial, with vastly different treatment approaches and prognoses.
  
  
  METHODS
  Patients treated with RT for LGGs through the Children's Hospital of Pittsburgh Neuro-Oncology Program are considered to have PP and managed conservatively if they develop increased mass effect within 3 years of RT. Pre-RT tumor area was compared to the maximum tumor size following RT and the size on the last follow-up scan by a central reviewer.
  
  
  RESULTS
  Twenty-four children, median age 13 years, received external beam RT for LGG between March 2000 and August 2011. Thirteen patients (54.2%) developed an increase in tumor size compared to baseline beginning at a median of 6 months after RT and lasting for a median of 2.1 years (range 6.5 months to 5.1 years). Maximum tumor enlargement occurred at a median of 8 months after RT, with a range (5 months to 4.2 years). In all 13 cases, the tumor eventually decreased in size without additional anti-tumor therapy. Two patients (8.3%) developed true tumor progression. With a median follow-up of 4.9 years (range 1.0-12.4 years), all patients are alive.
  
  
  CONCLUSIONS
  Pseudoprogression occurred in more than half of the children with LGG following RT, typically beginning within 8 months and often running a very protracted course. Late presentations can also occur.
authors.affiliation: Department of Neurosurgery, Children's Hospital of Pittsburgh, Neurosurgery/Faculty Pavilion, Pittsburgh, Pennsylvania.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Naftel
authors.forename: Ian F
authors.initials: IF
authors.lastname: Pollack
authors.forename: Giulio
authors.initials: G
authors.lastname: Zuccoli
authors.forename: Melvin
authors.initials: M
authors.lastname: Deutsch
authors.forename: Regina I
authors.initials: RI
authors.lastname: Jakacki
mesh_terms: D000293:Adolescent; D001932:Brain Neoplasms / Q000473:pathology / Q000532:radiotherapy; D002648:Child; D002675:Child, Preschool; D003952:Diagnostic Imaging; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005910:Glioma / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D060787:Neoplasm Grading; D011379:Prognosis; D011832:Radiation Injuries / Q000175:diagnosis / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects*; D015996:Survival Rate
keywords: low-grade glioma; pediatrics; pseudoprogression juvenile pilocytic astrocytoma; radiation