A Systematic Review and Meta-Analysis on the Number of Adjuvant Temozolomide Cycles in Newly Diagnosed Glioblastoma

BACKGROUND: In newly diagnosed glioblastoma, radiation with concurrent and adjuvant (six cycles) temozolomide (TMZ) is the established standard of postsurgical care. However, the benefit of extending adjuvant TMZ therapy beyond six cycles has remained unknown. METHODS: We searched PubMed, Web of Science, Scopus, and Embase up to October 1, 2021. The search keywords were "glioblastoma," "adjuvant chemotherapy," and their synonyms. The data of randomized clinical trials were extracted and included in this meta-analysis if they had reported patients' median overall survival (OS) or median progression-free survival (PFS). The standard and extended chemotherapy regimens were considered as adjuvant TMZ up to six cycles and beyond six cycles (up to a total of 12 cycles), respectively. The median OS and median PFS were pooled and compared. RESULTS: = 0.73]. CONCLUSIONS: In newly diagnosed glioblastoma, continuing adjuvant TMZ beyond six cycles did not shown an increase neither in PFS nor OS.