====== Fractionated stereotactic radiotherapy for vestibular schwannoma (FSRT) ======

Surgery is the mainstay of treatment and only after the introduction of single-fraction [[stereotactic radiosurgery]] (SRS), [[radiotherapy]] emerged as an alternative viable option. In a [[review]], Kalogeridi et al., focused on SRS or conventionally fractionated stereotactic radiotherapeutic (FSRT) approaches. They described the results of different doses used for SRS and FSRT, the current status, and a comparison between the two radiotherapy approaches. Stereotactic radiotherapy techniques aim to control tumor growth with minimal toxicity. SRS using either a [[cobalt]] unit or a [[linear accelerator]] has given high rates of tumor control and of cranial nerve function preservation with marginal doses range of 12-14 Gy. [[Fractionated stereotactic radiotherapy]] (FSRT) is optimal for tumors larger than 3 cm. Doses as low as 50.4 Gy provide excellent control rates and low morbidity. Overall, both SRS and FSRT are equally effective and safe options for [[vestibular schwannoma]] patients who do not need immediate surgical decompression
((Kalogeridi MA, Kougioumtzopoulou A, Zygogianni A, Kouloulias V. Stereotactic
radiosurgery and radiotherapy for acoustic neuromas. Neurosurg Rev. 2019 Apr 13. 
doi: 10.1007/s10143-019-01103-6. [Epub ahead of print] Review. PubMed PMID:
30982152.
)).
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A retrospective analysis included 162 patients who underwent radiation therapy for sporadic vestibular schwannoma (VS). Measurements on T1-weighted contrast-enhanced MRI (in 2-year post-therapy intervals: 0-2, 2-4, 4-6, 6-8, 8-10, 10-12 years) were taken for total tumour volume (TTV) and enhancing tumour volume (ETV) based on a semi-automated technique. Patients were considered non-responders (NRs) if they required subsequent microsurgical resection or developed radiological progression and tumour-related symptoms.

Median follow-up was 4.1 years (range: 0.4-12.0). TTV and ETV decreased for both the Fractionated stereotactic radiotherapy FSRT and SRS groups. However, only the FSRT group achieved significant tumour shrinkage (p < 0.015 for TTV, p < 0.005 for ETV over time). The 11 NRs showed proportionally greater TTV (median TTV pre-treatment: 0.61 cm3, 8-10 years after: 1.77 cm3) and ETV despite radiation therapy compared to responders (median TTV pre-treatment: 1.06 cm3; 10-12 years after: 0.81 cm3; p = 0.001).

3D quantification of VS showed a significant decrease in TTV and ETV on FSRT-treated patients only. NR had significantly greater TTV and ETV over time
((Schneider T, Chapiro J, Lin M, Geschwind JF, Kleinberg L, Rigamonti D,
Jusué-Torres I, Marciscano AE, Yousem DM. 3D quantitative assessment of response 
to fractionated stereotactic radiotherapy and single-session stereotactic
radiosurgery of vestibular schwannoma. Eur Radiol. 2015 Jul 3. [Epub ahead of
print] PubMed PMID: 26139318.
)).
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[[Fractionated stereotactic radiotherapy]] (FSRT) may preserve normal function and control both small and large [[vestibular schwannoma]]
((Williams JA. Fractionated stereotactic radiotherapy for acoustic neuromas. Int
J Radiat Oncol Biol Phys. 2002 Oct 1;54(2):500-4. PubMed PMID: 12243828.)).