Retrospective Monocentric Analysis of Carmustine Wafer Implantation in Recurrent Glioblastoma: Impact on Survival and Key Prognostic Factors

Objective: The implantation of biodegradable carmustine (BCNU) wafers is a treatment option for recurrent high-grade glioma (HGG), but its efficacy is debated. We evaluated its impact on overall survival (OS) and survival after recurrence (SAR) considering recurrence timing after first-line treatment. Methods: In this single-center retrospective study, we analyzed patients who underwent surgery for glioblastoma (GBM) recurrence following initial diagnosis (pre- and post-WHO classification 2016) between 2007 and 2022. All patients received standard first-line therapy, including maximal safe resection, radiotherapy with concomitant temozolomide, and adjuvant temozolomide. Recurrent GBM treatment involves resection, with or without adjuvant chemo- and/or radiotherapy. Patients who received carmustine wafer implantation (CWI) during resection were compared to those without wafer placement. Recurrences were classified by timing relative to first-line therapy: (1) post-radiochemotherapy, pre-adjuvant temozolomide; (2) during adjuvant temozolomide; (3) during prolonged temozolomide; (4) >1 month after completion of all therapy. Primary endpoints were OS and SAR, with prognostic factors analyzed. Results: A total of 176 patients were enrolled, with 59.7% (105/176) receiving CWI. Recurrence treatment included surgery without adjuvant therapy in 23.3% (41/176) of cases (26.7% of CWI+ and 18.3% of CWI−), adjuvant chemotherapy in 39.8% (70/176) (41% of CWI+ and 38% of CWI−), radiotherapy in 7.4% (13/176) (7.6% of CWI+ and 7% of CWI−), and combined radiochemotherapy in 29.5% (52/176) (24.8% of CWI+ and 36.6% of CWI−). No significant differences were found between groups in age (p = 0.684), residual tumor volume after initial (p = 0.988) or recurrence surgery (p = 0.356), MGMT status (p = 0.766) and KPS post 1st-line-therapy (p = 0.833). Median OS was 20 months range 18–24 for CWI+ and 22 months range 20–27 for CWI− (p = 0.487). The median SAR was 10 months range 8–12 for CWI+ and 12 months range 10–13 for CWI− (p = 0.252). Later recurrence (type 4) significantly correlated with prolonged OS (HR 0.16, 95% CI: 0.04–0.66, p = 0.011). Age (p < 0.001), MGMT methylation (p = 0.017), and smaller residual tumor volume post-recurrence surgery (p = 0.008) were also associated with longer survival. Conclusions: CWI did not significantly improve OS or SAR in recurrent GBM patients. However, younger age, MGMT methylation, smaller residual tumor volume, and later recurrence were linked to better survival outcomes, underscoring their prognostic importance.