Frameless Fractionated Stereotactic Radiosurgery for Vestibular Schwannomas: A Single-Institution Experience

Abstract

Objective: To examine tumor control, hearing preservation, and complication rates after frameless fractionated stereotactic radiosurgery (SRS) in patients with vestibular schwannomas (VS).Methods: Thirty-seven patients treated with fractionated SRS from 2002 to 2011 were retrospectively analyzed. Ninety-five percent were treated with 25 Gy in five fractions, targeting a median tumor volume of 1.03 cc (range 0.14–7.60).Results: With a median follow-up of 4.25 years (range, 15 months–9 years), no tumors required an additional treatment resulting in 100% tumor control rate. Radiographic control rate was 91% in 32 patients at a median follow-up of 3 years. Of the 14 patients with serviceable hearing and with audiograms, the hearing preservation rate was 78% at a median follow-up of 18 months. Twenty-six patients with serviceable hearing pretreatment, were evaluated by a phone survey with a hearing preservation rate of 73% at a 5 year median follow-up. There were two cases that developed both new increased trigeminal parasthesias and facial spasms but there were no cases of facial weakness. Patient had 96% of good to excellent satisfaction rate with the treatment at a median follow-up of 5 years.Conclusion: Frameless fractionated SRS treatment of VS results in good rate of tumor control. Hearing preservation rate and rates of cranial nerve toxicity are comparable to what is reported in the literature. Patients choose this modality because of its non-invasive nature and are generally very satisfied with their long term outcome.

The radiosurgery fractionation quandary: single fraction or hypofractionation?

“…There have been some studies examining the outcomes of patients with larger vestibular schwannomas treated with HF-SRS. The regimens ranged from 18-21 Gy in 3 fractions to 25 Gy in 5 fractions, resulting in similar local control, hearing preservation, and preservation of trigeminal and facial nerve functions, [63][64][65][66][67][68] as shown in Table 1. However, the follow-up times are typically much shorter than those for single-fraction SRS.…”

CyberKnife Radiosurgery of Skull-base Tumors: A UK Center Experience

“…As a result, although attempts were made to acquire first-hand clinical assessments of outcome, or to retrieve subsequent follow-up data from referring clinicians, this was not achieved in many cases. In hindsight, it is acknowledged that a prospective arrangement for follow-up, such as maintaining direct patient contact through post-treatment telephone consultation [ 29 ], would have improved the quantity and quality of post-treatment data collection.…”

Vestibular Schwannomas: Surgical and Nonsurgical Management

“…Evaluating success after STR is a challenge due to changes in technology, treatment protocols (radiation dose), and the relatively short duration of follow-up reported and variability in how treatment success is defined. Current studies have a mean follow-up of less than 5 years [31,36,[46][47][48][49][50], and long-term outcomes are often based on actuarial estimates of tumor control and hearing preservation rates [41-43, 46, 47]. There is also significant variability in how successful tumor control or hearing preservation is defined.…”

“…There is also significant variability in how successful tumor control or hearing preservation is defined. For example, some studies define successful tumor control as no growth on follow-up imaging [35,47,50,51], while others report a lack of symptomatic growth or progression that required further treatment [31,42,49]. To illustrate, Vivas [31] reported tumor growth rates and percentage of patients that progressed to further intervention.…”

“…7]. However, many studies reporting control rates fail to clarify whether the tumor demonstrated growth prior to STR [42,47,49,[51][52][53]. Therefore, in many studies, it is unclear if the lack of tumor growth is a result of STR or whether the tumor naturally was not growing.…”