Co-deletion of 1p/19q as Prognostic and Predictive Biomarker for Patients in West Bohemia with Anaplastic Oligodendroglioma

Background: Anaplastic oligodendrogliomas (AO) are rare tumors. Two phase III clinical trials (RTOG 9402 and EORTC 26951) proved favorable effects of radiotherapy (RT) with chemotherapy (procarbazine, lomustine and vincristine; PCV) in patients with AO carrying chromosomal mutation of co-deletion1p/19q even if it was not the primary endpoint of these studies. We assessed 1p/19q co-deletion as a prognostic and predictive biomarker for our patients with AO.

Materials and methods: 1p/19q co-deletion was assessed by fluorescence in situ hybridization in tumor samples from 23 patients and correlated with progression-free (PFS) and overall (OS) survival for the entire cohort and for the subgroups of patients with different treatment (neurosurgery plus RT alone vs. RT plus PCV).

Results: 1p/19q co-deletion was identified in 12 out of 23 tumors (52.2%). Patients with co-deletion had longer OS (587 vs. 132 weeks, p=0.012) and a trend for longer PFS (321 vs. 43 weeks, p=0.075). Patients with co-deletion treated with neurosurgery and RT plus PCV vs. neurosurgery and RT alone also had longer OS (706 vs. 423 weeks, p=0.008). There was no survival difference for patients without 1p/19q co-deletion in relation to treatment.

Conclusion: The prognostic value of 1p/19q co-deletion in our patients with AO was verified. The strong positive predictive value of this biomarker for OS was also shown for patients with co-deletion treated with neurosurgery and RT plus PCV vs. neurosurgery and RT alone.