Neurologic Tumors - Oligodendroglioblastoma

NCCN guidelines recommend identifying high-risk patients with glioblastoma for radiotherapy. High-risk features: 1. oligodendroglial or mixed oligodendroglial astrocytoma; 2. age <40 years; 3. KPS ≥70; 4. tumor diameter <6 cm; 5. minimal or no neurologic deficits; 6. 1p/19q double deletion with IDH1/2 mutation. High risk factors (3 or more risk factors): 1. astrocytoma; 2. age ≥40 years; 3. KPS <70; 4. tumor diameter ≥6 cm; 5. tumor midline; 6. preoperative neurologic deficit or not to a lesser extent neurologic dysfunction; 7. single deletion or absence of 1p/19q; 8. absence of mutation in IDH1/2. 1p/19q co-deletion was found in both grade I and II 80%-90% and 50%-70% in grade I and II oligodendrogliomas, respectively; 50%-70% in mesenchymal oligodendrogliomas; 30%-50% in oligodendroglial astrocytomas; and 20%-30% in mesenchymal oligodendroglial astrocytomas.The clinical significance of 1p/19q co-deletion differs from that of a single deletion of either 1p or 19q.In 2016, the NCCN noted that 1p/ 19q co-deletion in mesenchymal oligodendrogliomas and mesenchymal oligodendroglial astrocytomas cannot be treated with chemotherapy alone. Patients with single deletions or no deletions, however, may still choose chemotherapy alone. The presence of 1p/19q polysomes in patients with co-deletion of 1p/19q is often associated with shorter disease progression-free survival and overall survival independent of tumor grade. the presence of 1p/19q deletion correlates with the presence or absence of radiographic pseudoprogression. One study showed that the rate of pseudoprogression was 10 times higher in the 1p/19q nondeletion group than in the deletion group.