Stereotactically guided conformal radiotherapy for meningiomas.
OBJECTIVE
Stereotactically guided conformal radiotherapy, (SCRT) is a high precision technique of conformal radiotherapy (RT) which reduces the volume of normal tissue irradiated compared to conventional RT and may lead to a reduction in long-term toxicity We describe the technique and the preliminary results in patients with inoperable, residual or recurrent meningiomas.


METHODS
From July 1993 to November 1997, 24 patients (median age: 56 years, range: 28-72) with base of skull (n = 21). falx or upper skull (n = 3) meningiomas were treated with SCRT. The technique employed immobilization in a Gill-Thomas-Cosman (GTC) frame and CT localization with a Brown-Roberts-Wells (BRW) fiducial system for stereotactic space definition. The planning target volume (PTV) was defined as gross tumour volume (GTV) and a 0.5-1 cm margin. Treatment was delivered with three (12 patients) or four non-coplanar conformal fixed fields (12 patients) Conformal blocking was achieved either with lead alloy blocks (n = 11) or with a multi-leaf collimator (MLC) (n = 13). Patients were treated on a 6 MV linear accelerator to doses of 50-55 Gy, in 30-33 daily fractions. The treatments were carried out as part of a routine work of a busy radiotherapy department.


RESULTS
Median GTV for 24 meningiomas was 21.7 cm3 (range: 4.4-183 cm3). SCRT was well tolerated with minimal toxicity Three months after the end of radiotherapy, seven of 15 patients with neurological deficit had an improvement and eight remained unchanged. Two patients experienced early side effects (one VII nerve palsy, one Addisonian state). At a median follow-up of 13-months (range: 3-43) the 1 year progression free survival and overall survival are 100%. which is within the range expected for conventional fractionated radiotherapy for meningiomas.


CONCLUSIONS
SCRT is a feasible technique of high precision conformal RT for patients with meningiomas. Potential advantages in tumour control, survival and toxicity over conventional RT, require evaluation in long-term prospective studies.
Alheit
H
H
Academic Unit of Radiotherapy and Oncology, The Institute of Cancer Research and The Royal Marsden NHS Trust, Sutton, Surrey, UK.
Saran
F H
FH
Warrington
A P
AP
Rosenberg
I
I
Perks
J
J
Jalali
R
R
Shepherd
S
S
Beardmore
C
C
Baumert
B
B
Brada
M
M
D000328:Adult; D000368:Aged; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy*; D008579:Meningioma / Q000000981:diagnostic imaging / Q000401:mortality / Q000532:radiotherapy*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011859:Radiography; D020266:Radiotherapy, Conformal / Q000379:methods*; D012189:Retrospective Studies; D019291:Skull Base; D013238:Stereotaxic Techniques; D015996:Survival Rate; D016896:Treatment Outcome