Association of hospital volume with survival but not with postoperative mortality in glioblastoma patients in Belgium.

OBJECTIVES: Standard of care treatment for glioblastoma (GBM) involves surgical resection followed by chemoradiotherapy. However, variations in treatment decisions and outcomes exist across hospitals and physicians. In Belgium, where oncological care is dispersed, the impact of hospital volume on GBM outcomes remains unexplored. This nationwide study aims to analyse interhospital variability in 30-day postoperative mortality and 1-/2-year survival for GBM patients. METHODS: Data collected from the Belgian Cancer Registry, identified GBM patients diagnosed between 2016 and 2019. Surgical resection and biopsy cases were identified, and hospital case load was determined. Associations between hospital volume and mortality and survival probabilities were analysed, considering patient characteristics. Statistical analysis included logistic regression for mortality and Cox proportional hazard models for survival. RESULTS: A total of 2269 GBM patients were identified (1665 underwent resection, 662 underwent only biopsy). Thirty-day mortality rates post-resection/post-biopsy were 5.1%/11.9% (target < 3%/<5%). Rates were higher in elderly patients and those with worse WHO-performance scores. No significant difference was found based on hospital case load. Survival probabilities at 1/2 years were 48.6% and 21.3% post-resection; 22.4% and 8.3% post-biopsy. Hazard ratio for all-cause death for low vs. high volume centres was 1.618 in first 0.7 year post-resection (p < 0.0001) and 1.411 in first 0.8 year post-biopsy (p = 0.0046). CONCLUSION: While 30-day postoperative mortality rates were above predefined targets, no association between hospital volume and mortality was found. However, survival probabilities demonstrated benefits from treatment in higher volume centres, particularly in the initial months post-surgery. These variations highlight the need for continuous improvement in neuro-oncological practice and should stimulate reflection on the neuro-oncological care organisation in Belgium.

Impact of clinical target volume margin reduction in glioblastoma patients treated with concurrent chemoradiation.

Background: Glioblastoma (GBM) is widely treated using large radiotherapy margins, resulting in substantial irradiation of the surrounding cerebral structures. In this context, the question arises whether these margins could be safely reduced. In 2018, clinical target volume (CTV) expansion was reduced in our institution from 20 to 15 mm around the gross target volume (GTV) (ie, the contrast-enhancing tumor/cavity). We sought to retrospectively analyze the impact of this reduction. Methods: All adult patients with GBM treated between January 2015 and December 2020 with concurrent chemoradiation (60Gy/2Gy or 59.4Gy/1.8Gy) were analyzed. Patients treated using a 20 (CTV20, n = 57) or 15 mm (CTV15, n = 56) CTV margin were compared for target volumes, dose parameters to the surrounding organs, pattern of recurrence, and survival outcome. Results: Mean GTV was similar in both groups (ie, CTV20: 39.7cm3; CTV15: 37.8cm3; P = .71). Mean CTV and PTV were reduced from 238.9cm3 to 176.7cm3 (P = .001) and from 292.6cm3 to 217.0cm3 (P < .001), for CTV20 and CTV15, respectively. As a result, average brain mean dose (Dmean) was reduced from 25.2Gy to 21.0Gy (P = .002). Significantly lower values were also observed for left hippocampus Dmean, brainstem D0.03cc, cochleas Dmean, and pituitary Dmean. Pattern of recurrence was similar, as well as patient outcome, ie, median progression-free survival was 8.0 and 7.0 months (P = .80), and median overall survival was 11.0 and 14.0 months (P = .61) for CTV20 and CTV15, respectively. Conclusions: In GBM patients treated with chemoradiation, reducing the CTV margin from 20 to 15 mm appears to be safe and offers the potential for less treatment toxicity.