Radiosurgery is a well-established treatment for vestibular schwannomas (VSs), but it is often difficult to identify which tumors will respond to treatment. We sought to determine whether pretreatment or posttreatment tumor apparent diffusion coefficient (ADC) values could predict tumor control in patients undergoing Gamma Knife radiosurgery (GKRS) and whether these values could differentiate between cases of pseudoprogression and cases of true progression in the early posttreatment period.
We retrospectively identified patients who underwent GKRS for solid VSs between June 2008 and November 2016 and who had a minimum follow-up of 36 months. Pretreatment and posttreatment minimum, mean, and maximum ADC values were measured for the whole tumor volume and were compared between patients with tumor control and those with tumor progression. In patients with early posttreatment tumor enlargement, ADC values were compared between patients with pseudoprogression and those with true progression.
Of the 44 study patients, 34 (77.3%) demonstrated tumor control at final follow-up. Patients with tumor control had higher pretreatment minimum (1.35 vs 1.09; p = 0.008), mean (1.80 vs 1.45; p = 0.004), and maximum (2.41 vs 1.91; p = 0.011) ADC values than patients with tumor progression. ADC values did not differ between patients with pseudoprogression and those with true progression at early posttreatment follow-up.
ADC values may be helpful in predicting response to GKRS in patients with solid VSs but cannot predict which tumors will undergo pseudoprogression. Patients with higher pretreatment ADC values may be more likely to demonstrate posttreatment tumor control.
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The authors sincerely thank Megan Griffiths, ELS, for providing editorial assistance.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (name of institute/committee) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.
Conflict of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript. Non-relevant disclosures include the following: Varun R. Kshettry is a consultant for Integra LifeSciences and Stryker Corporation; Pablo F. Recinos is a consultant for Stryker Corporation.
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This article is part of the Topical Collection on Tumor – Schwannoma
A portion of this work was presented as an oral presentation at the North American Skull Base Society 29th Annual Meeting on February 17, 2019, in Orlando, FL.
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Soni, P., Potter, T., Poturalski, M. et al. Pretreatment ADC predicts tumor control after Gamma Knife radiosurgery in solid vestibular schwannomas. Acta Neurochir (2021). https://doi.org/10.1007/s00701-021-04738-x
- Acoustic neuroma
- Apparent diffusion coefficient
- Gamma Knife