Nitrosourea efficacy in high-grade glioma: a survival gain analysis summarizing 504 cohorts with 24193 patients
Large phase III studies have identified limited survival benefits with chemotherapy in high-grade glioma. However, numerous clinical trials have been published previously with smaller patient numbers and no control groups. A small positive effect could be missed this way, resulting in premature rejection of possible beneficial treatment. In order to perform a treatment arm summarizing analysis (TASA), a database was created summarizing treatments published between January 1976 and June 2002. In this database, one record represents a cohort of patients treated in the same way. Various patient cohort characteristics such as median age, and outcome measures including median overall survival times (mOS), were documented. Two-hundred and twenty publications were documented with a total number of 17,213 cases treated in 337 treatment groups. There was a statistically significant relationship between the distribution of histological grades (p<0.001) and the outcome, and a better outcome in younger patient populations (p<0.01). However, the known influence of the median Karnowsky performance scale could not be confirmed in this database. The extent of surgery showed a positive influence only when excluding relapse studies, while the positive effect of radiation was clear in all subgroups (p<0.05). Clinical studies that included nitrosurea in the treatment had a significantly better outcome than those with platinum drugs or without chemotherapy. We conclude that TASA, representing a novel way to perform a meta-analysis, is valid since it confirms the known treatment effects and, therefore, has the potential to provide new insights by combining information from different clinical treatment studies.