Patterns of recurrence and outcomes of glioblastoma multiforme treated with chemoradiation and adjuvant temozolomide

OBJECTIVES: To assess the patterns of failure and prognostic factors in Brazilian patients with glioblastoma multiforme (GBM) treated with radiotherapy (RT) and concurrent and adjuvant temozolomide (TMZ). METHODS: Patients with diagnosed GBM post-resection received postoperative RT. TMZ was administered concurrently at 75 mg/m(2)/day for 28 consecutive days and adjuvant therapy at 150-200 mg/m(2)/day for 5 days every 28 days. Radiographic failure was defined as any new T1-enhancing lesion or biopsy-confirmed progressive enhancement inside of the radiation field. When possible, patients with recurrence were salvaged with metronomic TMZ, either in combination with a local treatment or alone (surgery or re-irradiation). Several prognostic factors were evaluated for overall survival (OS). Univariate and multivariate analyses were performed to identify significant factors. A p-value <0.05 was considered significant. RESULTS: This study included 50 patients. The median follow-up time was 21 months. The median RT dose was 60 Gy and all patients received concomitant TMZ. During follow-up, 41 (83.6%) failures were observed, including 34 (83%) in-field, 4 (9.7%) marginal, and 3 (7.3%) distant failures. Metronomic TMZ was used as salvage treatment in 22 (44%) cases and in combination with local treatment in 12 (24%) cases. The median OS and progression-free survival times for the entire cohort were 17 and 9 months, respectively. In univariate analysis, the following factors were significant for better OS: maximal surgical resection (p=0.03), Karnofsky Performance Score (KPS)>70 at diagnosis (p=0.01), metronomic TMZ treatment (p=0.038), recursive partitioning analysis class III (p=0.03), and time to failure >9 months (p=0.0001). In multivariate analysis, the following factors remained significant for better OS: metronomic TMZ (p=0.01) and time to failure >9 months (p=0.0001). CONCLUSION: The median OS of Brazilian patients with GBM treated with RT and TMZ was satisfactory. Although TMZ therapy has become the standard of care for patients with newly diagnosed GBM, the recurrence rate is extremely high. Metronomic TMZ as salvage treatment improved survival in these patients.