COT-18 Trends in Primary Brain Tumors in Kumamoto Prefecture with Declining Birthrate and Aging Population - Kumamoto Prefecture Brain Tumor Epidemiological Survey

Backgrounds: The demographic characteristics of Kumamoto Prefecture are that there is little population movement and the total population remains constant at about 1.8 million, but in recent years the birthrate is declining and the population is aging. We have been conducting the Kumamoto Prefecture Brain Tumor Epidemiological Survey since 1989 in cooperation with neurosurgical institutions in the prefecture. In this study, we examined whether recent demographic changes have affected the incidence of primary brain tumors (BT). Methods: Patients with primary BT were collected annually from 44 institutions in Kumamoto Prefecture (as of 2020), and the number of incidences per 100,000 population was calculated for each BT for each year, excluding patients living outside the prefecture and duplicate cases. Results: The total number of primary BT was 11441 (top 3: meningioma 40%, pituitary adenoma 17%, glioma 17%). Of 4261 men with primary BT, the top 3 were meningioma (27%), glioma (23.7%), and pituitary adenoma (18.4%)), and 7180 women (top 3: meningioma (47.7%), pituitary adenoma (16.2%), and glioma (12.9%)). The number of primary BT increased every year, and the incidence increased significantly when comparing 1989–2004 and 2005–2020 (13.6 vs. 25.0/100,000, p<0.000001). Typical brain tumors (meningioma, pituitary adenoma, glioma, schwannoma, malignant lymphoma) also increased year by year, especially asymptomatic meningioma. The median age of asymptomatic meningiomas was significantly higher than that of symptomatic meningiomas (69 vs. 65 years, p<0.0001). Gliomas increased significantly in the later stages compared with the early stages in children (0–14 years) and the elderly (65 years and older). Conclusion: Our results suggest that an increase in the number of BT such as glioblastoma, which are more common in the elderly, as well as an increase in the number of opportunities for intracranial examinations in the aging of the population may be responsible for the increased incidence of primary BT.

Treatment of Asymptomatic Meningioma With Gamma Knife Radiosurgery: Long-Term Follow-up With Volumetric Assessment and Clinical Outcome

BACKGROUND Some patients are diagnosed with asymptomatic meningioma(s) after undergoing a screening CT and MRI for minor ailments or postresection. OBJECTIVE To help clinicians in decision making for treatment of asymptomatic meningiomas. METHODS A single center retrospective cohort study of 117 patients with 122 tumors treated with Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden). Patients were followed with longitudinal imaging and clinical evaluations. Tumor volumetry and developments of new signs or symptoms after GKRS were the end points in the study. RESULTS Median patient age at GKRS was 60 yr (range 21-86 yr) with a median clinical follow-up of 53 mo (range 20-252 mo). The median pre-GKRS tumor volume was 3.6 ± 3.8 cc (±standard deviation). Tumors were treated with a median margin dose of 14 ± 2 Gy. At last follow-up, median tumor volume was 2.5 ± 3.6 cc. Radiological progression-free survival (PFS) rates were 97% and 94.4% at 5 yr and 10 yr, respectively. Clinical PFS rates were 86% and 70% at 5 yr and 10 yr, respectively. Development of neurological complications was seen in 21 (18%) patients, and 11 (52%) of them had undergone surgical resection prior to GKRS. CONCLUSION GKRS is a reasonable treatment strategy for asymptomatic meningiomas and compares favorably to natural history studies in terms of tumor control and neurological preservation. It results in relatively low morbidity in previously untreated meningiomas and serves as an appealing alternative treatment modality for recurrent meningiomas in asymptomatic patients.

Clinical and radiological outcomes of proactive Gamma Knife surgery for asymptomatic meningiomas compared with the natural course without intervention

OBJECTIVEThis study aimed to verify the effect of proactive Gamma Knife surgery (GKS) in the treatment of asymptomatic meningioma compared with the natural course without any therapeutic intervention.METHODSFrom January 2006 to May 2017, 354 patients newly diagnosed with asymptomatic meningioma were reviewed and categorized into GKS (n = 153) and observation (n = 201) groups. Clinical and radiological progression rates were examined, and changes in volume were analyzed.RESULTSClinical progression (i.e., clinician-judged progression), combining symptomatic progression (n = 43) and clinician-judged increase in size using images routinely acquired (n = 34), occurred in 4 patients (2.6%) and 73 patients (36.3%) in the GKS and observation groups, respectively (p < 0.001). The clinical progression-free survival (PFS) rates in the GKS and observation groups were 98.7% and 64.6%, respectively, at 5 years (p < 0.001), and 92.9% and 42.7%, respectively, at 10 years (p < 0.001). The radiological tumor control rate was 94.1% in the GKS group, and radiological progression was noted in 141 patients (70.1%) in the observation group. The radiological PFS rates in the GKS and observation groups were 94.4% and 38.5%, respectively, at 5 years (p < 0.001), and 88.5% and 7.9%, respectively, at 10 years (p < 0.001). Young age, absence of calcification, peritumoral edema, and high T2 signal intensity were correlated with clinical progression in the observation group. Volumetric analysis showed that untreated tumors gradually increased in size. However, GKS-treated tumors shrank gradually, although transient volume expansion was observed in the first 6 months. Adverse events developed in 26 of the 195 GKS-treated patients (13.3%), including 1 (0.5%) major event requiring microsurgery due to severe edema after GKS. Peritumoral edema was related to the development of adverse events (p = 0.004).CONCLUSIONSAsymptomatic meningioma is a benign disease; however, nearly two-thirds of patients experience tumor growth and one-third of untreated patients eventually require neurosurgical interventions during watchful waiting. GKS can control tumors clinically and radiologically with high probability. Although the risk of transient adverse events exists, proactive GKS may be a reasonable treatment option when there are no comorbidities limiting life expectancy.