1) Surgery is the cornerstone of treatment for the majority of low-grade astrocytomas, while postoperative radiotherapy has been shown to lengthen the progression-free period without significantly affecting the overall survival - median survival is 7.
Compared with the differential diagnoses suggested when evaluating the conventional MRI, the multimodal MRI (MRS and/or PWI) provided additional information in 27 (61%) patients and helped to differentiate between lymphoma and GBM in 7 patients (4 GBM and 3 lymphomas); between GBM and metastases in 7 patients; between high-grade and low-grade astrocytomas in 5 patients; between various other tumours in 4 patients; and between tumours and non-neoplastic conditions in 4 patients (Table 3).
BRAF gene duplication constitutes a mechanism of MAPK pathway activation in
low-grade astrocytomas.
More sensitive and specific markers to distinguish low-grade astrocytoma from reactive gliosis will be welcome diagnostic adjuncts as intraocular biopsy evolves as a clinical resource.
17 Unlike most low-grade astrocytomas of the brain, they do not overexpress p53, nor do they display the K1AA-BRAF fusion mutation seen in pilocytic astrocytoma.
The median survival of patients with
low-grade astrocytomas is 5 years, and most patients die from progression of their disease to a high-grade astrocytoma.
Low-grade tumors, including
low-grade astrocytomas, oligodendrogliomas and mixed tumors, have been found over time to progress to high grade tumors.
71-74) These genetic abnormalities are rare in diffuse astrocytic gliomas and, therefore, may allow the differentiation of pilocytic astrocytomas from low-grade astrocytomas, especially if combined with IDH mutational analysis.
Duplication of 7q34 in pediatric low-grade astrocytomas detected by high-density single-nucleotide polymorphism-based genotype arrays results in a novel BRAF fusion gene.
