A clinical review of treatment outcomes in glioblastoma multiforme—the validation in a non-trial population of the results of a randomised Phase III clinical trial: has a more radical approach improved survival?

OBJECTIVE: Glioblastoma multiforme (GBM) accounts for up to 60% of all malignant primary brain tumours in adults, occurring in 2-3 cases per 100,000 in Europe and North America. In 2005, a Phase III clinical trial demonstrated a significant improvement in survival over 2, and subsequently 5, years with the addition of concurrent and adjuvant temozolomide (TMZ) to radical radiotherapy (RT). The aim of this study was to investigate if the demonstrated improved survival in the literature translated to clinical practice. METHODS: This was a retrospective study including all patients with histologically proven GBM diagnosed from 1999 to 2008 and treated with adjuvant RT at our institution. A total of 273 patients were identified. Statistical analysis was carried out using SPSS® v.18 (SPSS, Chicago, IL). RESULTS: The median survival for the whole group (n=273) over the 10-year period was 7.6 months (95% confidence interval 6.7-8.4 months). Overall, the cumulative probability of survival at 1 and 2 years was 31.5% and 9.4%, respectively. In total, 146 patients received radical RT. 103 patients were treated with radical RT and TMZ and 43 patients received radical RT alone. The median survival for patients receiving radical RT with TMZ was 13.4 months (95% CI 10.9-15.8 months) vs 8.8 months for radical RT alone (95% CI 6.9-10.7 months, p=0.006). 2-year survival figures were 21.2% vs 4.7%, respectively. On multivariate analysis, independent predictors of survival included Karnofsky Performance Status, RT dose, TMZ and extent of surgery. The strongest predictors of poorer outcome based on the hazard ratio were palliative RT, followed by not receiving TMZ chemotherapy, then KPS <90 and a biopsy only surgical approach. CONCLUSION: This paper demonstrates improved survival outcomes consistent with those published in the literature for the addition of concurrent and adjuvant TMZ to radical RT for the treatment of GBM. Although 63% of patients seen in the clinic were suitable for a combined modality approach, the prognosis for the lower Radiation Therapy Oncology Group classes still remains poor.