What dose/fractionation would you consider for salvage re-irradiation of a vestibular schwannoma after fractionated stereotactic radiation, >4 years later?

Salvage re-irradiation for vestibular schwannoma (VS) is far from "routine" for several reasons. First and foremost, progression of a small vestibular schwannoma after adequate SRS/FSRT is quite uncommon. More common is a phenomenon comparable to pseudoprogression, and the first and foremost component of assessment is to rule this out, if necessary, with more than one follow-up detailed imaging evaluation, with adequate interscan interval. This phenomenon is more common than progression after adequate treatment.

The next issue to address is to review all of the original imaging and planning to ensure that there was no geographic miss. If there was no geographic miss, be alert to the fact that very rarely, sarcomatous change has been reporte...