Oligodendroglioma is defined molecularly by co-deletion of chromosomal arms 1p and 19q. This co-deletion has which prognostic and predictive significance?

• A It predicts resistance to alkylating chemotherapy (temozolomide/PCV) and worsened prognosis
• B It indicates MGMT promoter hypermethylation independently
• C 1p/19q co-deletion defines glioblastoma multiforme and indicates IDH wildtype status
• D It predicts sensitivity to alkylating chemotherapy (PCV/temozolomide) and confers favorable prognosis among diffuse gliomas ✓

Explanation

Co-deletion of 1p and 19q is the defining molecular alteration of oligodendroglioma (along with IDH mutation, per WHO 2021 CNS classification). 1p/19q co-deletion predicts sensitivity to PCV chemotherapy (procarbazine, lomustine, vincristine) and temozolomide, and confers a significantly more favorable prognosis compared to IDH-mutant astrocytoma or glioblastoma. It is not associated with GBM (which is IDH-wildtype). MGMT methylation is a separate biomarker relevant to GBM chemosensitivity.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.