Loss of 1p, 19q, and 10q heterozygosity prospectively predicts prognosis of oligodendroglial tumors--towards individualized tumor treatment?

The purpose of this study was to determine whether chromosome 10q loss is a predictor of tumor aggressiveness and poor clinical outcome in patients with oligodendroglial tumors alone or together with loss of heterozygosity (LOH) on chromosomes 1p and 19q. A microsatellite analysis was performed on sections from 130 patients with grade II and grade III oligodendroglial tumors to assess the allelic status of chromosomes 1p, 19q, and 10q, plus detailed clinical and radiological information was taken prospectively. Median age at diagnosis was 45.5 years. Seventy-eight patients had disease progression after initial therapy; median progression-free survival (PFS) was 27.5 months. Age <47 years, postoperative Karnofsky performance score >65, no contrast enhancement on MRI, grade II, and complete removal on surgery were significantly correlated with a better PFS. Median overall survival (OS) was 40.5 months. Pure oligodendroglioma and temozolomide chemotherapy were correlated with better OS. 10q LOH was correlated with anaplastic grade and 1p19q LOH correlated with pure oligodendroglioma. There was a significant association between LOH status and the tumors' response to chemotherapy: 92.3% with 1p19q LOH, 83.3% without allelic losses, 50% with 1p19q10q LOH, and 14.5% with 10q LOH. Patients with 10q LOH alone had PFS of 6 months and a 3-year survival rate of 1%, when compared with 36 months and 85%, respectively, in patients with 1p19q LOH but without 10q LOH. 1p loss was correlated with better PFS (P < .005) and OS (P = .0007), whereas 10q loss was correlated with decreased PFS (P < .0001) and OS (P < .0001). 10q LOH predicted a survival disadvantage in patients with oligodendroglial tumors irrespective of 1p/19q LOH status.