Long-Term Clinical Outcomes of Pencil Beam Scanning Proton Therapy for Benign and Non-benign Intracranial Meningiomas

Int J Radiat Oncol Biol Phys. 2017 Dec 1;99(5):1190-1198. doi: 10.1016/j.ijrobp.2017.08.005. Epub 2017 Aug 12.


Purpose: To assess and report long-term clinical outcomes regarding local control, overall survival, and toxicity-free survival after pencil beam scanning proton therapy for intracranial meningiomas at a single institution.

Patients and methods: Ninety-six patients (male/female, 29/67; median age 52.8 years) with intracranial meningiomas (World Health Organization [WHO] grade 1, n=61 [63.5%]; WHO grade 2, n=33 [34.4%]; WHO grade 3, n=2 [2.1%]) were treated with pencil beam scanning proton therapy (n=53 [55.2%] at diagnosis, n=17 [17.7%] at recurrence, and n=26 [27.1%] for tumor progression). Median gross tumor volume before PBSPT was 21.4 cm3 (range, 0.0-546.5 cm3), with a median planning target volume of 123.4 cm3 (range, 4.6-1142.0 cm3). Median duration of follow-up was 56.9 months (range, 12.1-207.2 months). Late toxicity was graded according to the Common Terminology Criteria for Adverse Events, version 4.0.

Results: Thirteen failures (14%) (male/female, 6/7) were observed, of which the majority (n=9, 69%) were of non-benign histology. The 5-year actuarial local control and overall survival were 86.4% and 88.2%, respectively. Five-year grade ≥3 toxicity-free survival was 89.1%. On univariate analysis, local control was worse for patients with higher WHO grade (P≤.001), those treated after at least 1 recurrence (P=.006), those with non-skull base tumor location (P=.014), and males (P=.032). Significant prognosticators for 5-year overall survival were local control (P≤.001), age (P=.002), and timing of proton therapy (initial vs recurrence) (P=.002).

Conclusions: Pencil beam scanning proton therapy is an effective and safe treatment for patients with intracranial meningiomas, resulting in high local control rates with limited toxicity. Up-front radiation likely results in improved outcomes and should be considered, especially for patients with non-benign tumors and/or for those with incomplete resections.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Analysis of Variance
  • Child
  • Child, Preschool
  • Disease Progression
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Meningeal Neoplasms / mortality
  • Meningeal Neoplasms / pathology
  • Meningeal Neoplasms / radiotherapy*
  • Meningioma / mortality
  • Meningioma / pathology
  • Meningioma / radiotherapy*
  • Middle Aged
  • Neoplasm Grading
  • Neoplasm Recurrence, Local / radiotherapy*
  • Proton Therapy / adverse effects
  • Proton Therapy / methods*
  • Radiotherapy Dosage
  • Radiotherapy, Adjuvant / methods
  • Salvage Therapy / methods
  • Time Factors
  • Treatment Failure
  • Treatment Outcome
  • Tumor Burden / radiation effects