Gliadel therapy given for first resection of malignant glioma: a single centre study of the potential use of Gliadel

The results of a recently concluded phase III study have shown that Gliadel therapy ( biodegradable polymer impregnated with 3.85% BCNU placed into the surgical cavity) significantly prolongs survival and time to relapse in patients having initial resective surgery for malignant glioma followed by radiotherapy. The indications and exclusion criteria for patients in this study were well defined. To determine the relative frequencies of Gliadel 'eligible' and 'ineligible' patients, and differences in prognostic variables between these two cohorts, we conducted a review of all Edinburgh patients with an initial diagnosis of malignant glioma managed throughout the period of patient accrual into the phase III Gliadel study ( Edinburgh was one of 38 contributing centres). Independent predictors of outcome were taken from the MRC prognostic index. Analysis was done on an intention to treat basis. Only 25% of patients (14/56) with malignant glioma managed over this period were eligible for the Gliadel study and all were recruited. The patients in the study group were younger ( median 51 v. 59 years, p = 0.085); in better clinical grade ( median Karnofsky score 85 v. 80, p = 0.038); more likely to have resective surgery (86% v. 38%, p = 0.0001); more likely to have postoperative radiotherapy (93% v. 55%, p = 0.0001) and more likely to survive longer, even though one half of the Gliadel cohort received placebo, ( 66 v. 19 weeks, p= 0.06) than those not eligible. If the future use of Gliadel is limited to the eligibility criteria used in the phase III trial about 20% (95% confidence intervals 13 - 34%) of patients with newly diagnosed malignant glioma will receive this therapy.