Radiotherapy results in a modest improvement in survival, without reducing the quality of life or cognition, in elderly patients with glioblastoma. (ClinicalTrials.gov number, NCT00430911 [ClinicalTrials.gov].).

Gliomatosis cerebri (GC) is a rare disease, defined as a diffuse neoplastic glial cell infiltration of the brain. Diagnosis and management of GC are difficult. This study analyzed 296 individual cases (90 patients followed through the ANOCEF network, and 206 cases from the literature), aged 1 month to 85 years (median 42), sex ratio=1.31. Median survival was 14.5 months. It was higher for patients younger than 42 years (17 months vs. 13 months), with performance status>or=80 (27 months vs. 9 months), low grade gliomatosis (grade 2=20 months, grade 3=11.5 months, grade 4=8.5 months), oligodendroglial subtype (36 months compared to 14 months for mixed GC and 11 months for astrocytic GC). Male population was younger (median 39 years vs. 45), had a higher incidence of oligodendroglial GC (22% vs. 13%), which may explain their better prognosis (median survival 17 months vs. 11.5 months) than female population. Despite a high rate of stabilization, the impact on survival of whole brain radiotherapy, which carries the risk of severe toxicity, is still unclear. Up-front chemotherapy benefit to some patients and may be preferred to whole brain radiotherapy. However, the many bias of such retrospective heterogeneous data claim for multicentric clinical trials in this rare disease.

Purpose: To develop a tumor growth inhibition model for adult diffuse low-grade gliomas (LGG) able to describe tumor size evolution in patients treated with chemotherapy or radiotherapy.Experimental Design: Using longitudinal mean tumor diameter (MTD) data from 21 patients treated with first-line procarbazine, 1-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea, and vincristine (PCV) chemotherapy, we formulated a model consisting of a system of differential equations, incorporating tumorspecific and treatment-related parameters that reflect the response of proliferative and quiescent tumor tissue to treatment. The model was then applied to the analysis of longitudinal tumor size data in 24 patients treated with first-line temozolomide (TMZ) chemotherapy and in 25 patients treated with first-line radiotherapy.Results: The model successfully described the MTD dynamics of LGG before, during, and after PCV chemotherapy. Using the same model structure, we were also able to successfully describe the MTD dynamics in LGG patients treated with TMZ chemotherapy or radiotherapy. Tumor-specific parameters were found to be consistent across the three treatment modalities. The model is robust to sensitivity analysis, and preliminary results suggest that it can predict treatment response on the basis of pretreatment tumor size data.Conclusions: Using MTD data, we propose a tumor growth inhibition model able to describe LGG tumor size evolution in patients treated with chemotherapy or radiotherapy. In the future, this model might be used to predict treatment efficacy in LGG patients and could constitute a rational tool to conceive more effective chemotherapy schedules.