Efficacy and Survival Analysis of Long-term Temozolomide Chemotherapy for Glioblastoma

Objective : To investigate the efficacy, feasibility and survival of long-term temozolomide (TMZ) chemotherapy for glioblastoma (GBM). Methods : The data of 69 GBM patients initially treated between January 2019 and December 2021 were retrospectively analyzed. Patients were categorized into a standard treatment group (6 cycles, n = 36) and a long-term treatment group (> 6 cycles, n = 33). Clinical and pathological characteristics were compared to assess prognostic differences. Results : Among all patients, the median progression free survival (mPFS) of all patients was 16.5 months; the median overall survival (mOS) was 19.5 months. There were 33 patients in the long-term treatment group and 36 patients in the standard treatment group. mPFS of the two groups were 23.9 months and 10.3 months, respectively, and the difference was statistically significant ( P ＜0.001). The mOS of the two groups was 37.6 months and 17.8 months in the long-term treatment group and the standard treatment group, respectively, and the difference was statistically significant ( P < 0.001). Univariate regression analysis showed that PFS was correlated with lesion location ( P = 0.031), O6-methylguanine-DNA methyltransferase promoter methylation (MGMTmet) ( P = 0.021), Isocitrate Dehydrogenase (IDH) mutation ( P = 0.036), and TMZ chemotherapy cycles ( P = 0.001). The MGMTmet ( P = 0.021) and the number of chemotherapy cycles of TMZ ( P = 0.001) were related to OS. Multivariable Cox regression analysis indicated that the MGMTmet and the number of chemotherapy cycles of TMZ were the independent influencing factors of PFS and OS. Conclusion : Long-term TMZ treatment can prolong the progression free survival and overall survival of GBM patients.