Search for Circulating Tumour Cells in the Blood and/or Cerebrospinal Fluid in Patients With Recurrent Aggressive Meningiomas: Proof-of-concept Study

Inclusion Criteria: * Over 18 years of age * Operated on for a grade 2 or 3 meningioma at Montpellier University Hospital between 2015 and 2024 * Tumour expressing SSTR2A on the initial surgical specimen * Clinical and/or radiological recurrence as determined by MRI imaging (progression of a residual lesion OR appearance of a new lesion consistent with a meningioma at the surgical site or elsewhere) Exclusion Criteria: * Other active ongoing cancer * Contraindications to lumbar puncture: * Intracranial hypertension with meningioma exerting a mass effect and obstruction of the cerebrospinal fluid (CSF) pathway/risk of trans-tentorial or amygdalar herniation * Blood clotting disorder with risk of haematoma at the puncture site (anticoagulant treatment at therapeutic dose or antiplatelet therapy, thrombocytopenia or thrombopathy) * Infection at the puncture site * Pregnant or breastfeeding women (Article L.1121-5 of the French Public Health Code) * Persons deprived of their liberty by judicial or administrative decision (Article L.1121-6 of the French Public Health Code) * Persons who are subject to legal protection measures or who are unable to express their consent (guardianship, curatorship, judicial protection; Article L.1121-8 of the French Public Health Code) * Not affiliated with a social security scheme or beneficiary of such a scheme (Article L.1121-8-1 of the French Public Health Code) * Persons participating in another study that includes an ongoing exclusion period (Article L.1121-12 of the French Public Health Code) * Failure to obtain written informed consent