Three randomised controlled trials (RCTs) enrolling patients with newly diagnosed glioblastoma multiforme (GBM - a form of HGG) have studied chemotherapy with temozolomide during and after radiotherapy. This was compared with radiotherapy only.
Those who received temozolomide had an improved survival and delayed progression of the disease. The short-term adverse events associated with temozolomide are low but can be severe, while the long-term effects are unknown. No RCTs investigated the use of temozolomide in HGGs other than GBM. In recurrent GBM, temozolomide delayed progression but did not improve overall survival. In the elderly population (age over 60 years), temozolomide alone appears to be a suitable alternative to radiotherapy alone for primary therapy of GBM. Either treatment has similar overall survival, progression-free survival and quality of life, but there are possibly more adverse events with temozolomide.
All these trials enrolled highly selected patients with good prognostic features that are not entirely representative of all patients with HGG limiting the general applicability of these results.