INTRODUCTION: This study aims to evaluate volumetric and morphological changes following CyberKnife radiotherapy of vestibular schwannomas.
METHODS: Between March 2011 and December 2013, a total of 39 patients (15 males, 24 females; mean age 52 years; range, 19 to 86 years) who underwent CyberKnife hypofractionated radiotherapy were retrospectively analyzed. Tumor volume calculations were done by manual segmentation. Tumor morphology was classified by arbitrary cystic scaling. Local tumor control, tumor progression, transient swelling rates, and changes in tumor morphology were evaluated.
RESULTS: Local tumor control and transient swelling rates were 87% and 46%, respectively. Cystic tumors responded better than solid tumors to treatment as evidenced by volume reduction rates (87% vs. 58%), although local control rates were not significantly different (93% vs. 83%). Transient swelling rates were significantly higher in cystic tumors than in solid tumors (67% vs. 29%). Post-treatment volume changes were not correlated with gender, age group, or pre-procedural tumor volume.
DISCUSSION AND CONCLUSION: CyberKnife radiotherapy is an effective way of achieving local tumor control in patients with vestibular schwannomas. Although higher rates of volumetric regression would be expected in more cystic tumors than more solid tumors, local control rates are similar.