Stereotactic Radiosurgery for Vestibular Schwannomas: Tumor Control Probability Analyses and Recommended Reporting Standards

Scott G. Soltys, Michael T. Milano, Jinyu Xue, Wolfgang A. Tomé, Ellen Yorke, Jason Sheehan, George X. Ding, John P. Kirkpatrick, Lijun Ma, Arjun Sahgal, Timothy Solberg, John Adler, Jimm Grimm, Issam El Naqa

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: We sought to investigate the tumor control probability (TCP) of vestibular schwannomas after single-fraction stereotactic radiosurgery (SRS) or hypofractionated SRS over 2 to 5 fractions (fSRS). Methods and Materials: Studies (PubMed indexed from 1993-2017) were eligible for data extraction if they contained dosimetric details of SRS/fSRS correlated with local tumor control. The rate of tumor control at 5 years (or at 3 years if 5-year data were not available) were collated. Poisson modeling estimated the TCP per equivalent dose in 2 Gy per fraction (EQD2) and in 1, 3, and 5 fractions. Results: Data were extracted from 35 publications containing a total of 5162 patients. TCP modeling was limited by the absence of analyzable data of <11 Gy in a single-fraction, variability in definition of “tumor control,” and by lack of significant increase in TCP for doses >12 Gy. Using linear-quadratic–based dose conversion, the 3- to 5-year TCP was estimated at 95% at an EQD2 of 25 Gy, corresponding to 1-, 3-, and 5-fraction doses of 13.8 Gy, 19.2 Gy, and 21.5 Gy, respectively. Single-fraction doses of 10 Gy, 11 Gy, 12 Gy, and 13 Gy predicted a TCP of 85.0%, 88.4%, 91.2%, and 93.5%, respectively. For fSRS, 18 Gy in 3 fractions (EQD2 of 23.0 Gy) and 25 Gy in 5 fractions (EQD2 of 30.2 Gy) corresponded to TCP of 93.6% and 97.2%. Overall, the quality of dosimetric reporting was poor; recommended reporting guidelines are presented. Conclusions: With current typical SRS doses of 12 Gy in 1 fraction, 18 Gy in 3 fractions, and 25 Gy in 5 fractions, 3- to 5-year TCP exceeds 91%. To improve pooled data analyses to optimize treatment outcomes for patients with vestibular schwannoma, future reports of SRS should include complete dosimetric details with well-defined tumor control and toxicity endpoints.

Original languageEnglish (US)
Pages (from-to)100-111
Number of pages12
JournalInternational Journal of Radiation Oncology Biology Physics
Volume110
Issue number1
DOIs
StatePublished - May 1 2021

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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