Primary and secondary gliosarcomas: clinical profile and outcomes at the National Cancer Institute (P5.163)

Objective: Characterize the clinical features and outcomes of primary and secondary gliosarcoma (PGS, SGS) at the National Cancer Institute Background: Gliosarcomas are considered rare variants of glioblastoma characterized by the presence of biphasic glial and mesenchymal components. PGS is defined as arising de novo in contrast to SGS where the sarcoma component is noted at recurrence of an established glioblastoma. This study examined the clinical features and outcomes comparing PGS with SGS. Design/Methods: An IRB approved NCI protocol was used to identify all patients with pathologically confirmed diagnosis of gliosarcoma and record clinical and outcomes data. Results: We identified 28 patients with PGS and 15 patients with SGS. Sex ratio (male to female) was 2.1 for PGS and 0.9 for SGS, with a median age of 53 years in each group. Only 1 patient with SGS had a history of brain irradiation before the diagnosis of glioblastoma. The common sites for tumor location were frontal (36%), bi-lobar (36%) and temporal (21%) for PGS and parietal (40%), frontal (20%) and temporal (20%) for SGS. Two patients with PGS (7%) developed extra-cranial metastasis (spinal cord and metastatic angiosarcoma). The median overall survival for PGS was 17.2 months compared with 30 months for SGS from initial diagnosis of high-grade glioma (HGG) (p=0.049). Median progression-free survival was 5.9 months for PGS and 9.7 months for SGS, from the diagnosis of HGG with a median from the time of sarcomatous transformation of 4.6 months. Conclusions: These findings suggest that there may be a difference in the underlying tumor biology between PGS and SGS but that the presence of a sarcomatous component, either at diagnosis or with subsequent transformation may lead to a treatment refractory and aggressive cancer. To further elucidate the biologic differences between SGS and PGS, RNA sequencing studies are underway. Disclosure: Dr. Ranjan has nothing to disclose. Dr. Colwell has nothing to disclose. Dr. Gilbert has nothing to disclose. Dr. Park has nothing to disclose.