Glioblastoma and Increased Survival with Longer Chemotherapy Duration

INTRODUCTION: The five-year survival rate for patients with glioblastoma (GBM) is low at approximately 4.7%. Radiotherapy plus concomitant and adjuvant temozolomide (TMZ) remains the standard of care. The optimal duration of therapy with TMZ is unknown. This study sought to evaluate the survival benefit of two years of treatment. METHODS: This was a retrospective chart review of all patients diagnosed with GBM and treated with TMZ for up to two years between January 1, 2002 and December 31, 2011. The Kaplan-Meier method with log-rank test was used to estimate the progression-free survival (PFS) and the overall survival (OS). The results were compared to historical controls and data from previous clinical trials of patients treated up to one year. RESULTS: Data from 56 patients with confirmed GBM were evaluated. The OS probability was 54% (SE = 0.068) at one year, 28.3% (SE = 0.064) at two years, 17.8% (SE = 0.059) at three years, and 4% (SE = 0.041) at five years. Seven patients (12.5%) were treated with TMZ for two years. Their median time-to-progression was 28 months (95% CI = 5.0 – 28.0), and they had an increased survival probability at three years compared to other patients (log-rank test χ(2) (1, N = 56) = 19.2, p < 0.0001). CONCLUSIONS: There may be an advantage for a longer duration of TMZ therapy among patients with GBM, but the sample size was too small for generalization. A multicenter prospective study is needed to identify optimal duration of TMZ therapy.