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Potential
significance of (11)C-methionine PET as a marker for the
radiosensitivity of low-grade gliomas
Ribom
D, Engler H, Blomquist E, Smits A
Department
of Neuroscience, Neurology, University Hospital, SE-751 85 Uppsala,
Sweden. dan.ribom@neurologi.uu.se
The role for radiotherapy in patients with low-grade gliomas remains
controversial.
Two
large prospective studies have failed to demonstrate a
radiotherapeutic dose-response effect, and EORTC trial 22845 found no
difference in survival between patients receiving adjuvant
radiotherapy and those who received radiotherapy at tumour
progression.
The
aim of this retrospective study was to analyse the patterns of
carbon-11 methionine (MET) uptake on positron emission tomography
(PET) in tumours treated with immediate radiotherapy and in those
treated with delayed radiotherapy at the time of tumour
progression.
The
21 adult patients studied had histologically confirmed low-grade
gliomas and had undergone a pre-treatment PET scan and a follow-up PET
scan at the time of progression.
Eleven
of the patients had undergone initial radiotherapy a median of 5 weeks
after the surgical procedure.
The
median time to progression was 3.5 years for this group, compared with
1.6 years for the group with delayed radiotherapy (P=0.06).
At
the time of progression, non-irradiated tumours had a significantly
higher MET uptake (P=0.02) and a larger uptake volume (P=0.008)
compared with baseline, whereas irradiated tumours showed no
statistically significant change.
We
observed a correlation between high pre-treatment uptake of MET and
reduction in MET uptake in response to radiotherapy (P=0.008).
All
irradiated tumours recurred within the radiation field.
In
conclusion, our results demonstrate signs of a residual radiation
effect at the time of tumour progression in low-grade gliomas with
high pre-treatment uptake of MET.
Pre-treatment
methionine uptake may be a marker for the radiosensitivity of
low-grade gliomas.
PMID: 11976801 [PubMed - indexed for MEDLINE]
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