Retrospective review of prognostic factors, including 1p19q deletion, in low‐grade oligodendrogliomas and a review of recent published works

Abstract

The purpose of the present study was to investigate potential prognostic factors in low-grade oligodendrogliomas (LGOs), particularly 1p19q deletion, due to its proven prognostic significance in anaplastic oligodendrogliomas. We carried out a retrospective review of patients with a histological diagnosis of LGO between 1990 and 2000 in Auckland and Wellington, New Zealand. All cases underwent central histopathological review and FISH testing for 1p19q status. Univariate analysis of potential prognostic factors including 1p19q status, age, tumour size, tumour crossing midline, tumour enhancement, extent of surgery and seizures at diagnosis was carried out. Thirty-one patients were eligible and FISH testing was successful in 28 specimens (90%). Twenty-three specimens (82%) had 1p19q deletion; four (14%) had no 1p19q deletion; and one (4%) had 1p deletion alone. At a median follow-up of 87 months (0-147 months), median survival had not been reached and no significant difference in overall survival (OS) based on 1p19q status was detected (1p19q deletion OS 56%; 1p19q intact OS 0%; 1p deletion alone 100% (P = 0.38)). None of the other prognostic factors investigated reached statistical significance. We confirmed the high incidence (82%) of combined 1p19q deletion in LGOs and the feasibility of successful FISH testing in paraffin embedded specimens up to 10-years-old. Analysis of potential prognostic factors was limited by the lack of events during the follow-up period.

A better surgical resectability of WHO grade II gliomas is independent of favorable molecular markers

“…Interestingly, we found the contrary, that is, that 1p19q codeletion was in fine significantly correlated with a lower surgical resectability. Codeletion was shown to represent a favorable prognostic [32] as well as predictive [33] spontaneous factor in GIIG, correlated with overall survival. As a consequence, our original findings support the fact that an improved survival in higher EOR is not biased by a better tumor-intrinsic prognostic factor.…”

Quantitative proteomic analysis shows differentially expressed HSPB1 in glioblastoma as a discriminating short from long survival factor and NOVA1 as a differentiation factor between low-grade astrocytoma and oligodendroglioma

“…Five and 10 years survival rates for oligodendroglioma are 78 and 51 %, respectively, whereas among astrocytoma they are 65 and 31 %, respectively [ 7 , 8 ]. This survival rate difference is due partially to a better response of oligodendroglioma to chemotherapy, including temozolomide or PCV- procarbazin, 1-(2-cloroethyl)-3-cyclohexil-L-nitrosurea and vincristin [ 9 – 14 ] and to radiation therapy [ 15 , 16 ]. Therefore, further analysis of differential protein profiles of these glioma types may help to: 1) refine the histopathologic diagnosis, currently based mainly in morphologic characteristics, with large interobserver variability [ 17 , 18 ], and 2) detect molecular targets that may explain the difference of clinical outcome between low grade astrocytoma and oligodendroglioma.…”

Postoperative radiation therapy for low‐grade glioma

“…In addition to EORTC 22844 and 22845, 2 other randomized trials and several retrospective studies have attempted to define prognostic features to stratify patients into high‐ and low‐risk groups. Table 3 compares these studies; in addition to the Pignatti risk features, extent of surgical resection, tumor location, tumor grade, radiographic contrast enhancement, performance status, and molecular markers have all been found to be important prognostic factors in various retrospective studies 8‐20. In the SEER cohort, we found that Pignatti risk factors of age ≥40 years and midline extension were associated with adjuvant PORT, whereas histology and tumor size were not.…”

“…Table 3 compares these studies; in addition to the Pignatti risk features, extent of surgical resection, tumor location, tumor grade, radiographic contrast enhancement, performance status, and molecular markers have all been found to be important prognostic factors in various retrospective studies. [8][9][10][11][12][13][14][15][16][17][18][19][20] In the SEER cohort, we found that Pignatti risk factors of age 40 years and midline extension were associated with adjuvant PORT, whereas histology and tumor size were not. Extent of surgery was significant in our cohort and in several other studies, but not in the Pignatti risk features.…”