Stereotactic radiosurgery – for pinpoint fractionated irradiation of the tumor One study determined malignancy rates (“malignancy rate”) after radiosurgical treatment of acoustic neuromas (vestibular schwannomas) ranging from 0.04% after 15 to 0.3% after 12.5 years. The incidence (frequency of new cases) of malignant transformation (transition from normal growth-controlled cells to uncontrolled growth tumor cells) was reported to be 0.02% per year. Conclusion: Stereotactic radiosurgery of acoustic neuromas is safe! Caution is advised in high-risk groups (young patients; tumors ≥ 2.5 cm because of postradiogenic volume increase).
