Is Interstitial Chemotherapy with Carmustine (BCNU) Wafers Effective against Local Recurrence of Glioblastoma? A Pharmacokinetic Study by Measurement of BCNU in the Tumor Resection Cavity

The effectiveness of carmustine (BCNU) wafers on local recurrence of glioblastoma (GBM) remains contentious. We investigated the accumulating high-dose effects of BCNU released from the wafers on the survival of GBM patients by measuring BCNU concentration in the resection cavity of GBM over time. BCNU wafers (Gliadel(®)) were implanted with an Ommaya device in 15 patients, including 12 patients with GBM. BCNU concentrations in the tumor resection cavity were measured for 30 days postoperatively. The area under the curve (AUC)(all) was calculated from BCNU concentration curves, and the relationships between AUC(all) and survival, tumor phenotypes on MRI, and recurrence patterns were analyzed. The BCNU concentration was maximal 1 h postoperatively, rapidly decreased within 24 h, and remained relatively high for 7 days. GBM patients were classified into two groups: early recurrence (ER) and late or no recurrence (LN), using median progression-free survival as the cut-off. AUC(all) tended to be lower in the ER group than in the LN group, but the difference was not significant. MRI revealed that all patients in the ER group had highly invasive GBMs, whereas all patients in the LN group had less-invasive GBMs. A total of 9 patients experienced recurrence, with 6 local, 2 diffuse, and 1 disseminated patterns. No differences in AUC(all) were seen between local and non-local recurrence groups. Total BCNU concentrations did not correlate with tumor progression or survival. However, a high concentration of BCNU may have potential to provide some survival benefit for less-invasive type GBM.