Effect Of Long-term Adjuvant Temozolomide Chemotherapy On Adult Primary Glioblastoma Patients Survival

Objective: Glioblastoma multiforme(GBM)is the most common primary malignant central nervous system(CNS)tumor.The Stupp regimen is the standard treatment,although the optimal number of temozolomide(TMZ)treatment cycles remains controversial.We compared different adjuvant chemotherapy after surgery and concurrent chemoradiotherapy : Standard 6-cycle and more than 6-cycle TMZ adjuvant chemotherapy.The purpose of this study was to determine whether temozolomide long-term adjuvant chemotherapy benefits the survival of adult patients with primary glioblastoma.Methods: We performed a single center retrospective study of GBM patients that underwent total resection,concurrent chemoradiotherapy,and at least 6 cycles of adjuvant TMZ chemotherapy from June 2011 to August 2018.Patients were divided into 2 groups based on adjuvant TMZ treatment plan: Group A(n=27): standard6-cycle adjuvant TMZ therapy and Group B(n=26): >6 cycles of adjuvant TMZ therapy.Tumor progression data were obtained from electronic medical record review or follow-up imaging results.Primary endpoints were progression-free survival(PFS)and overall survival(OS).Continuous variables were analyzed by ANOVA,and the Kaplan-Meier method was used to evaluate PFS and OS.Univariate and multivariate COX analyses determined correlation between survival rates and covariates.Results: After the end of follow-up in August 2019,median PFS was 15 months in in Group A(95%CI 9.5-20.5)and 20.1 months in Group B(95%CI 15.9-24.4).Group A median OS was 19.4 months(95%CI 15.5-23.2),compared to 25.6 months in Group B(95%CI 20.4-30.8).The 2-year survival rate of Groups A and B was 36% was 66%,respectively(P=0.02).and 5-year survival was 7% in both.Multivariate Cox regression analysis showed that PFS was related to long-term adjuvant chemotherapy、IDH mutation、MGMT methylation and the number of lobes involved in tumor.OS was related to IDH mutation,Mgmt methylation and preoperative KPS score,but not long-period adjuvant chemotherapyConclusions: There was no statistically significant difference between the two groups in the overall survival,but Long-term adjuvant TMZ chemotherapy benefits PFS and2-year survival rate in GBM patients.Moreover,long-term TMZ adjuvant chemotherapy will not cause more adverse reactions than standard 6-cycle chemotherapy,we support the extension of adjuvant TMZ chemotherapy cycles in patients with primary GBM.