Clinical relevance of 1p and 19q deletion for patients with WHO grade 2 and 3 gliomas.

PURPOSE: To assess the frequency of chromosomes 1p and 19q deletions in gliomas and to correlate 1p deletion with prognosis in patients with grade 2 and grade 3 gliomas independently of histologic subtype.
METHODS: We retrospectively evaluated 208 patients with WHO grade 2 and 3 gliomas who had 1p/19q molecular studies performed between 2000 and 2004. DNA was extracted from tumor tissue and germline material and evaluated by PCR using microsatellite markers for each chromosome.
RESULTS: There were 113 men and 95 women with a median age at diagnosis of 40. Thirty-eight patients had a low-grade astrocytoma (A2), 58 low-grade oligodendroglioma (O2), 31 low-grade oligoastrocytoma (OA2), 21 anaplastic astrocytoma (A3), 37 anaplastic oligodendroglioma (O3), and 23 had an anaplastic oligoastrocytoma (OA3). Chromosome 1p analysis was performed in all patients and showed deletions in 105 patients (76% of O2, 42% of OA2, 21% of A2, 89% of O3, 17% of AO3, and 14% of A3). Chromosome 19q studies were performed in 118 patients and showed deletions in 46 (56% of O2, 45% of OA2, 27% of A2, 76% of O3, 11% of OA3 and 0% of A3). On multivariate analyses, chromosome 1p was a prognostic factor for prolonged PFS (HR = 1.75, P = 0.03) and OS (HR = 3.59, P = 0.02) in grade 2 gliomas but not for grade 3 (HR = 0.81, P = 0.7 for PFS; HR = 1.31, P = 0.7 for OS).
CONCLUSION: Chromosome 1p deletion is a significant positive prognostic marker in diffuse, grade 2 gliomas regardless of histologic subtype.