Gliosarcoma: A Multi-Institutional Analysis on Clinical Outcomes and Prognostic Factors.

Purpose: This study describes oncological outcomes and investigates prognostic factors for patients with gliosarcomas (GSM).

Methods: Histopathologically confirmed GSM patients who underwent treatment at five European institutions were retrospectively analyzed.

Results: We analyzed 170 patients with a median clinical follow-up time of 9.2 months. The majority received surgery (94.1%), postoperative radiotherapy (pRT, 81.8%), and temozolomide (TMZ)-based postoperative chemotherapy (66.5%). The median overall survival (OS) and progression-free survival (PFS) were 12.3 and 6.6 months, respectively. In the multivariable Cox regression analysis (MVA), the following factors were significantly associated with OS: age per year (hazard ratio (HR): 1.03, p < 0.001), subtotal resection (STR) versus biopsy only (HR: 0.15, p = 0.018), gross total resection (GTR) versus biopsy only (HR: 0.13, p = 0.011), pRT versus no pRT (HR: 0.20, p < 0.001), postoperative TMZ-based chemotherapy versus no postoperative chemotherapy (HR: 0.44, p = 0.003), MGMT promoter non-methylated versus methylated (HR: 1.79, p = 0.05), and tumor diameter per cm (HR: 1.15, p = 0.046). For PFS, the following factors were significantly associated in the MVA: GTR versus biopsy only (HR: 0.19, p = 0.026), pRT versus no pRT (HR: 0.36, p = 0.006), postoperative TMZ-based chemotherapy vs. no postoperative chemotherapy (HR: 0.39, p < 0.001), MGMT promoter status unknown versus methylated (HR: 1.69, p = 0.034), and tumor diameter per cm (HR: 1.18, p = 0.016). Sex, primary or secondary GSM, and TP53 mutational status were not significantly associated with OS or PFS.

Conclusions: Trimodal therapy comprising surgical resection, pRT and TMZ-based chemotherapy appears to have the most beneficial effect on survival in GSM patients. Smaller tumor size, younger age and methylated MGMT promoters are associated with improved survival. To our knowledge, this is the largest multi-institutional cohort study investigating outcomes and prognostic factors for GSM.