The Impact of 5-Year Tumor Doubling Time to Predict the Subsequent Long-Term Natural History of Asymptomatic Meningiomas.

Abstract

Meningiomas are the most frequent primary brain tumors. The long-term natural history of asymptomatic meningiomas remains unclear and difficult to predict accurately, however. The purpose of this study was to determine the subsequent course of asymptomatic meningiomas preceded by 5 years of no treatment. We retrospectively studied patients with radiologically suspected intracranial asymptomatic meningiomas preceded by 5 years of no treatment. We volumetrically measured the lesions' chronological changes during the initial 5 years to obtain the 5-year tumor doubling time (5y-TdT). A total of 201 cases met the inclusion criteria. They were further divided into 3 subgroups: those who remained asymptomatic (group A; 174 cases), those who developed neurological symptoms and underwent treatment (group B; 8 cases), and those who received intentional intervention for a preventative reason (group C; 19 cases). 5y-TdT of group B (median: 46.5 months) was significantly shorter than that of group A (median: 216.3 months) (P < 0.001). Progression-free survival (PFS) was significantly different between tumors that exhibited 5y-TdT ≥ 98.8 months and <98.8 months (P < 0.001). When we combined groups B and C and set the PFS endpoint as either disease progression or treatment, we found that more than 20% of patients would require treatment within 15 years. The present study revealed the subsequent course of asymptomatic meningiomas after 5 years of no treatment and demonstrated that 5y-TdT is useful to detect patients who may require treatment.