The length of time from either the date of diagnosis or the start of treatment for a disease, such as cancer, that patients diagnosed with the disease are still alive. In a clinical trial, measuring the overall survival is one way to see how well a new treatment works. Also called OS.
Although overall survival (OS) is the standard for determining Glioblastoma treatment efficacy, using OS as an endpoint when studying new therapeutic strategies can be problematic because of potential influence of therapies prior to or subsequently following the therapy being studied. For example, it is difficult to definitively conclude that bevacizumab has no efficacy in GBM when a large percentage of patients in the placebo arms in both III trials studying efficacy of bevacizumab (i.e. AVAglio and RTOG-0825) eventually crossed over and received bevacizumab (31% in AVAglio trial 1) and 48% in RTOG 0825 2).
Preoperatively measured necrosis volume and necrosis-tumor ratio (NTR) are the most important radiological features of GBM with a strong influence on OS. No other measuring techniques are specific enough and comparable with 3D segmentation 3).