Clinical characteristics and prognosis of patients with glioblastoma with infratentorial leptomeningeal dissemination

Objective: Leptomeningeal dissemination (LMD) is a severe complication of glioblastoma (GBM) and has become a more common and indispensable clinical proposition with improved patient prognosis. Although infratentorial leptomeningeal dissemination (ITD) of GBM is rare, it is clinically significant as it may largely influence patient prognosis. Here, we investigated the clinical characteristics and prognosis of patients with ITD.Methods: Data of patients with newly diagnosed isocitrate dehydrogenase (IDH)-wildtype GBM treated at our institution between October 2008 and December 2018 were reviewed. ITD was defined as the dissemination of GBM, which first emerged as a supratentorial tumor, and later disseminated in the infratentorial region as the first recurrent site.Results: Of 160 patients with newly diagnosed IDH-wildtype GBM, seven (4.4%) were classified as having ITD. ITD lesions were in the fourth ventricle in two patients, extra-cerebellum or extra-brainstem in two, and intra-cerebellum in three. The primary symptoms of ITD were gait disturbance (85.7%, n=6), nausea and vomiting (28.6%, n=2), cerebellar mutism (14.3%, n=1), and none (14.3%, n=1). In four cases (57.1%), symptoms were confirmed before ITD discovery.The median progression-free survival (PFS) and overall survival of the patients were 12.2 and 19.7 months, respectively. Radiotherapy was performed in five patients, and all the patients received chemotherapy. The PFS and overall survival rates from ITD diagnosis were 2.9 and 7.1 months, respectively. Patients with favorable prognoses were younger and had higher Karnofsky performance status (KPS) scores.Conclusions: Radiotherapy or molecular-targeted therapy may be effective in some cases of ITD and may contribute to extending survival. Carefully checking the infratentorial region of patients with GBM during follow-up and rapidly treating ITD before their KPS score starts declining are crucial.