Imaging timing after surgery for glioblastoma: an evaluation of practice in Great Britain and Ireland (INTERVAL-GB)- a multi-centre, cohort study

Abstract

Purpose: Post-operative MRI is used to assess extent of resection, monitor treatment response and detect progression in high-grade glioma. However, compliance with accepted guidelines for follow-up MRI, and impact on management/outcomes is unclear.

Methods: Multi-center, retrospective observational cohort study of patients with confirmed WHO grade 4 glioma (August 2018-February 2019) receiving oncological treatment.

Primary objective: investigate follow-up MRI surveillance practice and compliance with recommendations from NICE (Post-operative scan < 72h, MRI every 3-6 months) and EANO (Post-operative scan < 48h, MRI every 3 months).

Results: There were 754 patients from 26 neuro-oncology centers with a median age of 63 years (IQR 54-70), yielding 10,100 (median, 12.5/person, IQR 5.2-19.4) person-months of follow-up. Of patients receiving debulking surgery, most patients had post-operative MRI within 72 h of surgery (78.0%, N = 407/522), and within 48 h of surgery (64.2%, N = 335/522). The median number of subsequent follow-up MRI scans was 1 (IQR 0-4). Compliance with NICE and EANO recommendations for follow-up MRI was 52.8% (N = 398/754) and 24.9% (N = 188/754), respectively. On multivariable Cox regression analysis, increased time spent in recommended follow-up according to NICE guidelines was associated with longer OS (HR 0.56, 95% CI 0.46-0.66, P < 0.001), but not PFS (HR 0.93, 95% CI 0.79-1.10, P = 0.349). Increased time spent in recommended follow-up according to EANO guidelines was associated with longer OS (HR 0.54, 95% CI 0.45-0.63, P < 0.001) but not PFS (HR 0.99, 95% CI 0.84-1.16, P = 0.874).

Conclusion: Regular surveillance follow-up for glioblastoma is associated with longer OS. Prospective trials are needed to determine whether regular or symptom-directed MRI influences outcomes.

Keywords: Glioblastoma; MRI; Neuro-oncology; Neuroimaging.

Fig. 1

Distribution of MRI scan time following surgery stratified by extent of resection. Each dot represents an MRI scan and each row of dots represents a patient. GTR = gross total resection; STR = subtotal resection

Fig. 2

Differences in interval imaging compliance stratified by extent of resection groups, Stupp protocol completion, and WHO performance status (PS). Fully compliant = a group that had every follow-up scan within the recommended time period; Inbetween = a group that had mixed periods of compliance with imaging, and mixed periods of non-compliance during follow-up; Never compliant = a group that had no imaging carried out within the recommended timeframe. STUPP protocol = full completion of STUPP protocol (adjuvant radiotherapy + concomitant and adjuvant chemotherapy); Other STUPP = Any other treatment (partial completion, no treatment)

Fig. 3

Kaplan–Meier estimates of A) OS stratified by NICE imaging compliance (Full, Inbetween, Never), B) OS stratified by first progression detected by scheduled vs unscheduled MRI