C. Thilmann et al., Intensity-modulated radiotherapy with an integrated boost to the macroscopic tumor volume in the treatment of high-grade gliomas, INT J CANC, 96(6), 2001, pp. 341-349
Integrated boost radiotherapy (IBRT) delivers a higher fraction size to the
gross tumor volume and a conventional fraction size to the surrounding tis
sue of microscopic spread. We compared stereotactic conformal radiotherapy
(SCRT) and intensity-modulated radiotherapy (IMRT) with regard to their sui
tability for IBRT in the treatment of high-grade gliomas. In 20 patients tr
eated with conventional radiotherapy, an additional treatment plan for IBRT
[planning target volume (PTV1) defined as contrast-enhancing lesion plus m
argin due to setup errors 75 Gy, PTV2 defined as edema plus margin due to m
icroscopic spread and setup error 60 Gy] with 7 non-coplanar beams for IMRT
and for SCRT was carried out and compared. The part of the PTV2 irradiated
with more than 107% of the prescribed dose was 13.9% for IMRT and 30.9% fo
r SCRT (P < 0.001). Dose coverage of PTV2 (volume above 95% of the prescrib
ed dose) was improved with IMRT (88.4% vs. 75.3% with SCRT, P < 0.001). Dos
e coverage of PTV1 was slightly higher with SCRT (93.7% vs. 87.5% with DART
), but the conformity to the boost shape was improved by IMRT [conformity i
ndex (COIN95) = 0.85 vs. 0.69 with SCRT]. Simultaneously the brain volume i
rradiated with > 50 Gy was reduced from 60 to 33 cc (P < 0.001). We conclud
e that IMRT is suitable for local dose escalation in the enhancing lesion a
nd for delivering a homogeneous dose to the PTV2 outside the PTV1 at the sa
me time. Our encouraging results justify application of IMRT for IBRT in th
e treatment of high-grade gliomas. For clinical evaluation a phase III stud
y has been initiated. (C) 2001 Wiley-Liss, Inc.