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Dhayalan D, Perry A, Graffeo CS, Tveiten ØV, Muñoz Casabella A, Pollock BE, Driscoll CLW, Carlson ML, Link MJ, Lund-Johansen M. Salvage radiosurgery following subtotal resection of vestibular schwannomas: does timing influence tumor control? J Neurosurg 2023; 138:420-429. [PMID: 35907189 DOI: 10.3171/2022.5.jns22249] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 05/17/2022] [Indexed: 02/04/2023]
Abstract
OBJECTIVE The goal of microsurgical resection of vestibular schwannoma (VS) is gross-total resection (GTR) to provide oncological cure. However, a popular strategy is to halt the resection if the surgical team feels the risk of cranial nerve injury is imminent, achieving a maximally safe subtotal resection (STR) instead. The tumor remnant can then be treated with stereotactic radiosurgery (SRS) once the patient has recovered from the immediate postoperative period, or it can be followed with serial imaging and treated with SRS in a delayed fashion if residual tumor growth is seen. In this study, the authors evaluated the efficacy of this multimodality approach, particularly the influence of timing and dose of SRS on radiological tumor control, need for salvage treatment, and cranial nerve function. METHODS VS patients treated with initial microsurgery and subsequent radiosurgery were retrospectively included from two tertiary treatment centers and dichotomized depending on whether SRS was given upfront (defined as before 12 months) or later. Radiological tumor control was defined as less than 20% tumor volume expansion and oncological tumor control as an absence of salvage treatment. Facial and cochlear nerve functions were assessed after surgery, at the time of SRS, and at last follow-up. Finally, a systematic literature review was conducted according to PRISMA guidelines. RESULTS A total of 110 VS patients underwent SRS following microsurgical resection, with a mean preradiosurgical tumor volume of 2.2 cm3 (SD 2.5 cm3) and mean post-SRS follow-up time of 5.8 years (SD 4.1 years). The overall radiological tumor control and oncological tumor control were 77.3% and 90.9%, respectively. Thirty-five patients (31.8%) received upfront SRS, while 75 patients (68.2%) were observed for a minimum of 12 months prior to SRS. The timing of SRS did not influence the radiological tumor control (p = 0.869), the oncological tumor control (p = 0.560), or facial nerve (p = 0.413) or cochlear nerve (p = 0.954) function. An escalated marginal dose (> 12 Gy) was associated with greater tumor shrinkage (p = 0.020) and superior radiological tumor control (p = 0.020), but it did not influence the risk of salvage treatment (p = 0.904) or facial (p = 0.351) or cochlear (p = 0.601) nerve deterioration. CONCLUSIONS Delayed SRS after close observation of residuals following STR is a safe alternative to upfront SRS regarding tumor control and cranial nerve preservation in selected patients.
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Affiliation(s)
- Dhanushan Dhayalan
- 1Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.,3Department of Clinical Medicine, University of Bergen, Norway; and
| | - Avital Perry
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | | | | | | | - Bruce E Pollock
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Colin L W Driscoll
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.,4Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota
| | - Matthew L Carlson
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.,4Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota
| | - Michael J Link
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.,4Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota
| | - Morten Lund-Johansen
- 1Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.,3Department of Clinical Medicine, University of Bergen, Norway; and
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