Application of the MRC brain tumour prognostic index to patients with malignant glioma not managed in randomised control trial

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Abstract
OBJECTIVES The MRC brain tumour prognostic index, which uses clinical variables to place patients in different outcome categories, has not been evaluated on a cohort outside a randomised controlled trial. The aims of this study were to (a) determine in a large cohort of patients, derived solely from one centre and not in a clinical trial, whether the MRC prognostic index stratified patients for outcome; (b) compare actual outcomes with those obtained in the original studies; and (c) examine whether neuropathological diagnosis was an independent prognostic variable. METHODS The MRC prognostic index was calculated for 236 patients with either glioblastoma or anaplastic astrocytoma managed at a dedicated neuro-oncology clinic in Edinburgh between 1989 and 1995. RESULTS For this mixed population of malignant glioma the median survival was 8.6 months. Two year survival was 72.2% for patients with an MRC index score of 1–10; 36.3% for those with an index score of 11–15; 25.1% for those scoring 16–20; 20.4% with those scoring 21–25; 4.8% with those scoring 26–33; and 0% for those scoring 34–38. Exclusion of 79 patients who would not have been eligible for the MRC studies from which the index was derived, because they were either too old or did not receive radiotherapy, still resulted in a similar pattern of stratification but with significantly improved median survival times for the lowest two categories. Multivariate analysis of prognostic variables in the Edinburgh cohort showed that patients with anaplastic astrocytoma did significantly better than those with glioblastoma (pCONCLUSIONS Although there were some differences in median survival times between the patients in the original MRC studies and the Edinburgh cohort in similar prognostic categories and a tendency to improved two year survivorship in the Edinburgh cohort these differences have arisen because (a) the Edinburgh cohort was accrued about 10 years later than the MRC cohorts and thus had optimal radiotherapy; and (b) many Edinburgh patients were included in experimental and other chemotherapy studies on relapse. This study has shown that even outside the setting of a prospective controlled trial and with relaxed inclusion criteria the Medical Research Council (MRC) prognostic index is a robust predictor of outcome in patients with malignant glioma. Survival clearly declines as the prognostic index increases. Moreover, the prognostic model can be substantially improved by the addition of histology data, although there is some evidence that this will require complex modelling procedures.