Monitoring of Patients With Diffuse Gliomas Using Circulating miRNAs

Diffuse gliomas are the most common primary tumors of the central nervous system, representing around 3,400 cases per year in France (Defossez et al., 2019). Their grade varies from 2 to 4. Whatever the grade, their prognosis is dismal (Grade 2: median survival \> 10 years, Grade 3: median survival around 5 years, Grades 4: median survival \< 2 years) (Yang et al., 2016). Grade 4 diffuse gliomas are the most common gliomas. Their treatment is based on excision of the tumor as completely as possible while preserving the patient's neurological functions. This surgical treatment is followed by a "Stupp" radiochemotherapy protocol (Stupp et al., 2005). Nevertheless, recurrence of grade 4 gliomas after surgery is inevitable, and usually occurs within 2 years of surgery (Pineda et al., 2023). In fact, gliomas are infiltrating tumors, with tumor cells infiltrating the brain parenchyma up to 2 cm from the periphery of the tumor visualized on MRI, which explains their inevitable recurrence, since surgery cannot be wide (it is difficult to achieve "safety margins" at the cerebral level) and will invariably leave tumor cells in situ (Pallud et al., 2013). In the event of recurrence, second-line chemotherapy or further surgery may then be proposed to the patient. Patients are monitored by regular brain MRI scans, but it is important to be aware of the risks involved.