Prognostic value of 1D, 2D, and volumetric tumor size increases in recurrent WHO grade 2 and 3 meningiomas: Radiological post-hoc analysis of the EORTC-BTG-1320 trial.

Background: Although the differential prognostic value of 1D, 2D, and volumetric meningioma size assessment has been reported, RANO meningioma criteria rely on bidimensional measurements.

Methods: In this post-hoc analysis of the EORTC-BTG 1320 trial, contrast-enhancing CNS WHO grade 2 and 3 meningiomas were assessed using 1D, 2D, and volumetric measurements. Different cutoff values for lesion size increase were compared 6 months after the start of antineoplastic treatment using Cox proportional hazards models to evaluate their association with overall survival (OS). Optimal cutoff values were identified using two criteria: maximal hazard ratio (HR) for death with statistical significance for median OS and the cutoff that maximized mean specificity and sensitivity for predicting 1-year OS.

Results: Among 57 evaluable patients, unidimensional 5 mm and 10 mm tumor size increase yielded the maximal HRs (HR = 3.41, 95% Confidence Interval (CI) 1.56-7.45,  < .01 and HR = 3.22, 95% CI 1.58-6.58,  < .01, respectively) for OS. A 6 mm tumor size increase maximized mean specificity and sensitivity (HR = 2.91, 95% CI 1.43-5.93,  < .01) for predicting 1-year OS. For tumor volume assessments, a 30% increase was associated with the maximal HR (HR = 3.69, 95% CI 1.64-8.31,  < .01) for OS whereas a 40% increase maximized the mean specificity and sensitivity (HR = 3.66, 95% CI 1.75-7.654,  < .01). Bidimensional measurements showed no significant OS association.

Conclusion: Unidimensional tumor measurements and tumor volume assessments show a stronger association with overall survival than bidimensional measurements in recurrent non-benign meningiomas. Integration of these methods into response assessment criteria for meningiomas should be considered.