Symptomatic Outcomes in Relation to Tumor Expansion After Fractionated Stereotactic Radiation Therapy for Vestibular Schwannomas: Single-Institutional Long-Term Experience

Journal Article · Fri Feb 01 04:00:00 EST 2013 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2012.05.003· OSTI ID:22149754

Aoyama, Hidefumi ^[1]; Onodera, Shunsuke ^[1]; Takeichi, Norihito ^[2]; Onimaru, Rikiya ^[1]; Terasaka, Shunsuke; Sawamura, Yutaka ^[3]; Shirato, Hiroki ^[1]

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1. Department of Radiation Medicine, Hokkaido University Graduate School of Medicine, Sapporo (Japan)
2. Department of Otolaryngology, Hokkaido University Graduate School of Medicine, Sapporo (Japan)
3. Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo (Japan)

Purpose: The effect of transient tumor expansion after conventionally fractionated stereotactic radiation therapy (SRT) on the symptomatic outcomes is not well-known. Methods and Materials: This study enrolled 201 consecutive patients who received SRT for vestibular schwannoma. A conventional fractionation schedule was applied in 194 patients (97%), and 142 (71%) received a total dose of 50 Gy. The median follow-up time was 72 months. Results: The maximum diameter was 9 mm or less in 13 patients, 10-19 mm in 79 patients, 20-29 mm in 87 patients, and 30 mm or greater in 22 patients. At presentation, tumor size of 20 mm or greater was significantly associated with loss of serviceable hearing and trigeminal neuropathy. After SRT, tumor expansion was observed in 42 patients (21%). By tumor size, tumor expansion was observed in 0%, 11.4%, 25.6%, and 50% of patients with tumors of 9 mm or less, 10-19 mm, 20-29 mm, and 30 mm or greater, respectively, in diameter. The tumor expansion was significantly associated with an increased risk of hydrocephalus requiring shunt placement (P=.004), loss of serviceable hearing (P=.0064), and worsening of facial (P<.0001) and trigeminal nerve (P<.0001) functions. Spontaneous tumor shrinkage was observed in 29 of those 42 patients, mostly within 2 years after the expansion, and the majority of the worsened symptoms except for hearing resolved once the tumor had shrunk. As a result, salvage surgical resection for symptomatic relief was required in only 5% of patients. Conclusions: Fractionated SRT could be safely applied even for medium- to large-sized ({>=}20 mm) tumors. However, greater knowledge of the risks and consequences, including transient symptomatic worsening, and the time span of expansion will be required for the follow-up of patients after SRT to avoid unnecessary surgical intervention.

• OSTI ID: 22149754
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 85; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
HEALTH HAZARDS
HEARINGS
LOSSES
MALFORMATIONS
NEOPLASMS
PATIENTS
RADIATION DOSES
RADIOTHERAPY
SHRINKAGE
SURGERY
SYMPTOMS