Artikel
Prognostic value of 18F-FET PET, MRI and cytoreduction in 61 low-grade glioma
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Veröffentlicht: | 28. April 2011 |
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Objective: This long-term study investigates prognostic factors in patients with untreated, non-enhancing, supratentorial low-grade glioma.
Methods: In a prospective study starting in 1999, baseline O-(2-[18F] fluoroethyl)-L-tyrosine (18F-FET) PET and MRI were performed on 61 patients (38 men – 23 women, mean age 38 years) with histologically confirmed glioma WHO grade II. We evaluated initial 18F-FET uptake, morphologic tumor features in MRI and therapeutic parameters (initial biopsy vs. cytoreduction). Statistical endpoints were clinical or radiologic tumor progression, malignant transformation to high-grade glioma and death. FET uptake with a maximum tumor/brain ratio of ≥1.6 was rated as positive.
Results: The median observation time reached 85 months (range 2–216 months). Initial tumor diagnosis was confirmed by biopsy (n = 34) or operation with cytoreduction (n = 27) and histology revealed 48 astrocytomas, 7 oligoastrocytomas and 6 oligodendrogliomas WHO grade II. The median progression free survival (PFS) of the group was 27 months, the median overall survival (OAS) 45 months. FET-uptake: In the majority of patients (n = 46) the initial PET showed a FET positive tumor. During the further course a malignant transformation was diagnosed in 18 (39%), PFS was 23.5 months, OAS 39 months. In 15 patients the tumor was FET negative. In one (7%) a malignant transformation was observed, PFS reached 57 months, OAS 64.5 months (pPFS = 0.02; pOAS = 0.01). MRI features: A diffuse tumor was diagnosed in 16 patients. In 8 (50%) malignant transformation was observed, PFS was 21 months, OAS 39 months. 42 patients showed a circumscribed tumor. In 11 (26%) a malignant transformation was observed, PFS reached 31 months, OAS 58 months (p value was not significant). Cytoreduction: 10 patients (37%) presented a tumor malignization in the course of therapy; neither PFS (28 vs. 26 months) nor OAS (45 vs. 47 months) showed a significant difference between the resection and the biopsy group.
Conclusions: While cytoreductive surgery (vs. biopsy only) at the time of first diagnosis seems to have no benefit for patients outcome, the morphologic and metabolic aspects of initial MRI and 18F-FET PET are strong prognostic predictors in low-grade glioma. A diffuse tumor with an early amino-acid uptake is at high risk for early progression, malignant transformation and death. In contrast circumscribed tumors with low initial 18F-FET uptake exhibit a long and stable course with late progress into a high-grade glioma.