Artikel
Stereotatic fractionated radiotherapy reduces tumour volume of meningiomas significantly
Die stereotaktisch fraktionierte Radiotherapie reduziert signifikant das Tumorvolumen von Meningeomen
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Veröffentlicht: | 23. April 2004 |
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Gliederung
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Objective
Since 1998, 111 patients (WHO I°: 59 pts., WHO II°: 5 pts., WHO III°: 4 pts., and primary RT: 43 pts.) suffering from skull base meningiomas were treated by stereotactic fractionated radiotherapy (FSRT). The local tumour control was excellent, only 1 pt. (WHO II°) developed a tumour recurrence during the follow-up of 30 months. Ninty-one pts. (98.9%) showed an equal or reduced tumour volume (TV). Visually, 1/3 of the pts. developed a regress of the TV by comparing MRI scans before and after FSRT. The aims of this study were to analyse TV reduction quantitatively and to determine factors leading to tumour shrinkage.
Methods
56 pts. (50 female, 6 male) were examined under equal conditions (i.e. same technique and MRI scanner) before and after FSRT: 6, 12 months and later. The median follow-up was 26 months. They all received a daily dose of 1.8-2.0 Gy up to a cumulative dose of 54-60 Gy. Fat saturated T1-weighted MRI scans with a thickness of 3 mm were analysed. MRI before and after FSRT were correlated, and the TVs were drawn in each slice. Afterwards, TVs before and after FSRT were compared.
Results
Median initial TV (mean + SD) was 13.8 ml (19.2 + 19.6) with a range from 0.4 to 90.2 ml. TV declined to a mean value of 16.2 + 17.9 ml, according to a mean shrinkage of 19.7% 6 months after FSRT. This decrease was highly significant (p<0.001). Twelve -18 months after FSRT mean shrinkage was 23.2%. Age at start of treatment showed a tendency for less intense shrinking with increasing age (p>0.05). A stratification into two groups, under 55 years and 55 years and older at treatment revealed a significant mean decrease in tumour volume of 22.4% and 16.8% (p<0.05), respectively. Furthermore, a significant correlation between initial TV and mean shrinkage was noticeable. Smaller TV (<13.8 ml) shrank about 23.5% and larger TV (>13.8 ml) about 15.9% (p=0.02). The most intense reduction of TV was found 6-12 months after FSRT, when TV reduction decreased towards a steady state, this has not yet been defined.
Conclusions
FSRT is a very effective method for the treatment of skull base meningiomas. An approx. 20% reduction in tumour volume is seen within one year. Smaller tumours and younger age are factors determining the extent of TV shrinking.