Objective: Surgery is the primary treatment modality for endolymphatic sac tumors (ELST). Two case examples are presented to highlight some rare instances when radiation therapy may be used. The outcomes following radiation therapy for ELST are controversial. This report systematically reviews those outcomes and compares results between external beam radiation and stereotactic radiosurgery.
Data source: In accordance with PRISMA guidelines a systematic literature search of the Ovid Medline, Embase, Scopus, Cochrane library, and clinicaltrails.gov databases was performed in August 2017.
Study selection: Twenty-two studies met inclusion criteria and report ELST outcomes following radiation therapy. Additional data on tumor size, previous surgery, radiation modality, and radiation dosing was collected.
Data extraction: The methodological quality was independently assessed by three reviewers. The included studies were small, heterogeneous case reports with a low level of evidence, and several sources of bias.
Data synthesis: The primary outcome was tumor control following radiation, defined as no growth. A comparative analysis of external beam versus stereotactic radiation was performed.
Conclusion: Forty-six tumors from 42 patients were independently analyzed. The overall tumor control rate was 67.4%. When analyzing patients in which tumor was present at the time of radiation, external beam radiation controlled 9 of 19 tumors (47.4%) while stereotactic radiosurgery controlled 14 of 18 tumors (77.8%). The effect size of 30.4% favors stereotactic radiosurgery, but the wide confidence interval (-4.4 to 57.4%) limits what conclusions can be drawn. Radiation for ELST remains controversial and more long-term data is needed.