Integrative assessment of brain and bone invasion in meningioma patients

Various prognostic factors have been suggested in meningioma patients including WHO grading, brain invasion and bone involvement, for instance. Brain invasion was included as an independent criterion in the recent WHO classification. However, assessability of brain or bone involvement is often limited or varies between histopathologic, operative and imaging reports. Objective of our study was to investigate prognostic values including brain and bone involvement according to different clinical approaches.

A cohort of 111 patients was treated with primary, adjuvant or salvage irradiation between 2008 and 2017 using intensity-modulated radiotherapy. Positron-emission tomography (PET) was available for treatment planning in 81% of patients. Clinical data were extracted from the medical reports. Brain and bone involvement were stratified separately according to histopathologic, operative and imaging reports as well as judged in synopsis.

WHO grade I tumours, lower estimated proliferation index, primary versus recurrence treatment and localization (i.e. skull base, optic nerve sheath) were beneficial prognostic factors for local control. Judgement of brain and bone invasion partly differed between diagnostic modalities. In synopsis, brain or bone invasion did not show a significant influence on local control rates.

Several previously described prognostic factors could be reproduced. However, partly divergent histopathological, surgical and image-based judgements could be found in regard to brain and bone invasion and all methods imply limitations. Therefore, we suggest a particular, complemental synopsis judgement. In synopsis, brain or bone involvement did not coherently impair local control in our irradiated patients. This might be explained by elaborate radiation techniques and PET-based treatment planning.