Impact of Tumour Cell Infiltration on Treatment Outcome in Gamma Knife Radiosurgery: A Modelling Study

Anticancer Res. 2019 Apr;39(4):1675-1687. doi: 10.21873/anticanres.13273.

Abstract

Background: High-grade gliomas with a widespread infiltration beyond the lesion detectable on diagnostic images are increasingly treated with Gamma Knife™ Radiosurgery (GKRS). The aim of this study was to assess the cell infiltration impact on the GKRS outcome for invasive gliomas.

Materials and methods: Tumor cell distribution was predicted using a novel algorithm whose computations are iterated until they reach an agreement with histopathology results. Treatment plans with different combinations of dose prescription (20 Gy at 50%-20% isodose) and targets [Gross Tumour Volume (GTV), zone 1 with 100%-60% of the GTV cell density and zone 2 with 60%-0% of the GTV cell density] were evaluated using standard conformity indexes (CI) and radiobiological parameters.

Results: Considerable differences in terms of tumor control probability were found between plans having similar CI but different targets.

Conclusion: To account for tumor cell infiltration outside the target is of key importance in GKRS and a radiobiological evaluation should accompany well-established CI.

Keywords: Gamma Knife; glioma; modelling; tumor cell infiltration.

MeSH terms

  • Algorithms*
  • Brain Neoplasms / pathology
  • Brain Neoplasms / radiotherapy*
  • Cell Movement*
  • Clinical Decision-Making
  • Computer Simulation
  • Glioma / pathology
  • Glioma / radiotherapy*
  • Humans
  • Neoplasm Grading
  • Neoplasm Invasiveness
  • Radiosurgery*
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted / methods*
  • Treatment Outcome