Article
Volume of lower-grade gliomas is inversely proportional to molecular features
Das Volumen von niedriggradigeren Gliomen ist indirekt proportional zur Expression bestimmter molekularer Marker
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Authors
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Aleksandrs Krigers
- Medizinische Universität Innsbruck, Universitätsklinik für Neurochirurgie, Innsbruck, Austria
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Johannes Kerschbaumer
- Medizinische Universität Innsbruck, Universitätsklinik für Neurochirurgie, Innsbruck, Austria
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Mathias Demetz
- Medizinische Universität Innsbruck, Universitätsklinik für Neurochirurgie, Innsbruck, Austria
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Claudius Thomé
- Medizinische Universität Innsbruck, Universitätsklinik für Neurochirurgie, Innsbruck, Austria
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Christian F. Freyschlag
- Medizinische Universität Innsbruck, Universitätsklinik für Neurochirurgie, Innsbruck, Austria
| Published: | June 26, 2020 |
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Outline
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Objective: Volumetric expansion is known to be a prognostic factor for the survival of LGG patients. The aim of our study was to correlate incidental discovery of LGG with tumour volumetry and imaging parameters including the WHO grades, presence of anaplastic foci and molecular markers.
Methods: From our database we could identify 99 consequent patients with histologically proven lower-grade gliomas. All underwent their first resection in our institution. The volume on MRI was measured in T1 CE and native, T2, FLAIR and DWI sequences. Molecular markers, neuropathological, epidemiological and clinical data were analysed in correlation to volumetric assessment.
Results: In our series 47 (47%) tumours were diffuse (WHO°II), 16 (16%) showed focal anaplasia (WHO°II-III) and 26 (26%) were anaplastic (WHO°III). IDH1 was mutated in 51 (71%) and wildtype in 21 (29%) cases. ATRX was expressed in 34 (62%) and lost in 21 (38%) LGG samples. Patients with IDH1 mutation were significantly younger with a mean age of 41 years (SE ±2) vs. 53 years (SE ±4, p=0.004).
The tumours with IDH1 mutation showed significantly lower level of anaplastic features – 24/51 vs 16/21, p=0.007; and had a trend towards loss of ATRX expression 17/37 vs. 3/16, p=0.061. Surprisingly, no significant differences were found regarding EGFR expression.
IDH1 mutation demonstrated a significant impact on volume in preoperative MRI compared to wildtype: in T1 – median 34.6 cm3 vs. 14.0 cm3 (p=0.035); in T2 – 33.7 cm3 vs. 14.3 (p=0.012), in FLAIR – 46.5 cm3 vs. 18.4 cm3 (p=0.021). The contrast enhancement tended to be less advanced in IDH1 mutated tumours, however, this difference was not significant, p=0.093. The tumours with ATRX loss were significant larger on preoperative MRI scans and had less CE.
The extent of resection did not differ considering IDH1 or ATRX status with median complete resection and mean – 95% (SE ±3) for CE volumes and 83% (SE ±3) for not enhancing volumes in T1 sequence. Consequently, the resected volume of the tumour was larger in case of loss of ATRX expression and IDH1 mutation. In cases with IDH1 mutation the clinical PFS after the resection was significantly higher with a mean 77 months (SE ±4) vs. 59 months (SE ±2), p<0.05.
Conclusion: Tumour volumes were inversely proportional to molecular markers. IDHwt gliomas seem to be diagnosed earlier with lower volumes as compared to IDHmut. The extent of resection was uninfluenced by the molecular strata of the tumours.
