Abstract
Stereotactic radiosurgery is a technique designed to produce a specific radiobiologic effect within a sharply defined target volume in a single session. Radiosurgery is a potentially effective alternative to surgical removal of small-sized to moderate-sized acoustic tumors. During a 12-year period, 556 patients with acoustic tumors underwent radiosurgery at the University of Pittsburgh, which represents 25% of all tumor radiosurgery cases. Our technique for acoustic tumor radiosurgery evolved steadily in the 1990s. The current technique of radiosurgery includes MR imaging-based conformal dose planning and 13 Gy minimal tumor dose. Preservation of cochlear and facial nerve function is the main concern during radiosurgery dose planning. For moderate-sized tumors, preservation of trigeminal nerve and brain stem function is a consideration. In our recent analysis, the 5-year acturial rates of preoperative hearing level preservation and speech preservation were 71% and 91% for 192 patients treated with 13 Gy as the median tumor margin dose. This dose was associated with 1.1% risk of new facial weakness and a 2.6% risk of facial numbness (5-year actuarial rates). The acturial 5-year clinical tumor control rate (no requirement for surgical intervention) was 97%. All patients (100%) with intracanalicular tumors treated at 13 Gy margin dose maintained a serviceable level of hearing. The results after radiosurgery of acoustic tumors have established it as an important minimally invasive alternative to microsurgery.
Published Version
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