Chromosome 1p and 19q evaluation in low-grade oligodendrogliomas: a descriptive study.

Oligodendrogliomas are rare primary brain tumors with variable patient outcomes which are not always adequately accounted for by clinical or pathological variables. The present study evaluated the prognostic implications of chromosome 1p and 19q status in a set of 23 low grade oligodendrogliomas (OGD II), and correlated the results with patient outcome. Loss of heterozygosity (LOH) and fluorescent in situ hybridization (FISH) analyses, the most widely used standard procedures, were used. 1p and 19q deletions were found in 65 and 61% of cases, respectively, using FISH and in 78 and 72% of cases using LOH. Both deletions were found in 56 and 64% of patients using FISH and LOH, respectively. Concordance between the results from the two techniques, determined by the Kappa statistics, ranged from fair to substantial depending on whether single or combined deletions were considered. Our results showed that the molecular alterations are associated with age and tumor localization. With regard to the impact of chromosomal alterations on clinical outcome, chromosome 19q deletions detected by LOH would seem to indicate a subgroup of patients at a higher risk of relapse, although the small number of patients recruited does not permit any definitive conclusions to be drawn. Further studies are now ongoing to determine whether this methodological approach could be potentially useful in low grade oligodendrogliomas to better characterize chromosomal alterations of 1p/19q and identify subgroups of patients with a higher risk of disease recurrence.