Co-polysomy of chromosome 1q and 19p predicts worse prognosis in 1p/19q codeleted oligodendroglial tumors: FISH analysis of 148 consecutive cases.

BACKGROUND This study aimed to evaluate the prognostic significance of co-polsomy of chromosome 1q and 19p in 1p/19q codeleted oligodendroglial tumors (ODGs). METHODS In a series of 148 ODGs with 1p/19q deletion, co-polysomy of 1q and 19p was detected by fluorescence in situ hybridization (FISH). Log-rank analysis and Cox regression methods were used to compare Kaplan-Meier plots and identify factors associated with worse prognosis. RESULTS There were 104 (70.3%) low-grade ODGs and 44 (29.7%) high-grade ODGs. Co-polysomy was independently associated with shorter progression-free survival and overall survival in 1p/19q codeleted ODGs, irrespective of tumor grades. The odds ratio of without and with co-polysomy was 0.263 (95% confidence interval [CI], 0.089-0.771; P = .015) for progression-free survival and 0.213 (95% CI, 0.060-0.756; P = .017) for overall survival. Subgroup analysis confirmed this trend in both low-grade and high-grade ODGs, although the P value for high-grade ODGs was marginally significant. CONCLUSIONS Co-polysomy of 1q and 19p could be used as a marker to independently predict worse prognoses and guide individual therapy in 1p/19q codeleted ODGs.