Fractionated stereotactic radiotherapy for acoustic neuromas.
BACKGROUND
When compared to radiosurgery, fractionated stereotactic radiotherapy (FSR) for acoustic neuroma (AN) offers escalation of tumor dose (Gy) and potential sparing of auditory and facial nerve functions.


METHODS
Over the past 6.5 years 287 consecutive patients have received FSR for AN. One hundred fifty patients have follow up greater than 1 year and comprise this report. Non-invasive, repeat-fixation mask allowed simulation via spiral CT. Differential collimation and beam weighting achieved conformality. Three distinct schedules for total dose and fractionation were used. For AN<3.0 cm diameter (mean volume 1.5+/-0.2 cc), > or =3.0 and < or =3.9 cm (mean volume 8.7+/-1.0 cc) and > or =4.0 cm (mean volume 28.3 cc (one case) doses of 5 Gy given in 5 consecutive daily fractions (25 Gy total) (131 patient), 10 fractions of 3 Gy (30 Gy total) (18 pts), or 20 fractions of 2 Gy (1 patient) were given. All treatments were prescribed to the 80% isodose and given via the dedicated 10 MeV accelerator.


RESULTS
The percentage decreases in tumor size were 14+/-1 (range: 0-100), 15+/-3 (range 0-38) and 8 for the 25, 30 and 40 Gy regimens, respectively. No patient had growth of AN or developed facial weakness. Two patients developed transient decrease in facial sensation. Rates of hearing preservation were similar for both the larger and smaller tumors.


CONCLUSIONS
Fractionated stereotactic radiotherapy may preserve normal function and control both small and large acoustic neuromas.
Williams
J A
JA
Department of Neurosurgery and Department of Oncology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street/Hunterian 817, Baltimore, MD 21205, USA.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001299:Audiometry; D003056:Cochlear Nerve / Q000503:physiopathology / Q000528:radiation effects / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005154:Facial Nerve / Q000503:physiopathology / Q000528:radiation effects / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000503:physiopathology / Q000601:surgery*; D009464:Neuroma, Acoustic / Q000503:physiopathology / Q000601:surgery*; D016634:Radiosurgery; D020127:Recovery of Function / Q000502:physiology; D013997:Time Factors