title: Disease control after reduced volume conformal and intensity modulated radiation therapy for childhood craniopharyngioma.
abstract: OBJECTIVE
  To estimate the rate of disease control after conformal radiation therapy using reduced clinical target volume (CTV) margins and to determine factors that predict for tumor progression.
  
  
  METHODS
  Eighty-eight children (median age, 8.5 years; range, 3.2-17.6 years) received conformal or intensity modulated radiation therapy between 1998 and 2009. The study group included those prospectively treated from 1998 to 2003, using a 10-mm CTV, defined as the margin surrounding the solid and cystic tumor targeted to receive the prescription dose of 54 Gy. The CTV margin was subsequently reduced after 2003, yielding 2 groups of patients: those treated with a CTV margin greater than 5 mm (n=26) and those treated with a CTV margin less than or equal to 5 mm (n=62). Disease progression was estimated on the basis of additional variables including sex, race, extent of resection, tumor interventions, target volume margins, and frequency of weekly surveillance magnetic resonance (MR) imaging during radiation therapy. Median follow-up was 5 years.
  
  
  RESULTS
  There was no difference between progression-free survival rates based on CTV margins (>5 mm vs ≤5 mm) at 5 years (88.1% ± 6.3% vs 96.2% ± 4.4% [P=.6386]). There were no differences based on planning target volume (PTV) margins (or combined CTV plus PTV margins). The PTV was systematically reduced from 5 to 3 mm during the time period of the study. Factors predictive of superior progression-free survival included Caucasian race (P=.0175), no requirement for cerebrospinal fluid shunting (P=.0066), and number of surveillance imaging studies during treatment (P=.0216). Patients whose treatment protocol included a higher number of weekly surveillance MR imaging evaluations had a lower rate of tumor progression.
  
  
  CONCLUSIONS
  These results suggest that targeted volume reductions for radiation therapy using smaller margins are feasible and safe but require careful monitoring. We are currently investigating the differences in outcome based on host factors to explain the results.
authors.affiliation: St Jude Children's Research Hospital, Radiological Sciences, Memphis, TN 38105, USA. thomas.merchant@stjude.org
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Merchant
authors.forename: Larry E
authors.initials: LE
authors.lastname: Kun
authors.forename: Chia-Ho
authors.initials: CH
authors.lastname: Hua
authors.forename: Shengjie
authors.initials: S
authors.lastname: Wu
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Xiong
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sanford
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Boop
mesh_terms: D000293:Adolescent; D002557:Cerebrospinal Fluid Shunts; D002648:Child; D002675:Child, Preschool; D003397:Craniopharyngioma / Q000208:ethnology / Q000473:pathology / Q000532:radiotherapy*; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010911:Pituitary Neoplasms / Q000208:ethnology / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated; D047368:Tumor Burden