The use of adjuvant radiotherapy in resected adult intracranial atypical meningioma in United States: A SEER analysis.

Abstract

27 Background: It is unclear whether adjuvant external beam radiotherapy (EBRT) in atypical meningiomas after surgical resection provided overall survival advantage. Although meta-analysis were previously reported, there is heterogeneity in the included studies. With lack of prospective trial, we rely on observational data for management. This project aims to determine if the addition of adjuvant EBRT after resection compared to resection alone in atypical meningioma is associated with better prolonged survival among patients within United States. Methods: The National Cancer Institute Surveillance, Epidemiology and End Results database was queried for list of patients diagnosed with atypical meningioma from 2000 to 2020 according to International Classification of Disease (ICD) for Oncology, third edition with morphology codes 9539/0 and 9539/1.This was limited to intracranial location. Rate of dying among those receiving adjuvant EBRT after surgery for atypical meningiomas was compared to the rate of dying of those who had resection alone without adjuvant EBRT postoperatively. Other covariates included, age at diagnosis, gender, marital status, race, tumor laterality, tumor site, tumor, extent of resection and household median income. Chi-squared test was used to test the association between institution of adjuvant EBRT and other co-variates for categorical variable. Cox-proportional analysis was used to test the association between adjuvant EBRT and death. Observed survival was estimated using Kaplan-Meyer method. Survival curves were generated for both cohorts and log rank test was performed. Results: A total of 3,328 patients were included in analysis.1,004(30.17%) patients received adjuvant EBRT and 767(23.05%) died in the entire cohort. Rate of dying in the entire cohort is 43.84 per 1,000 person-years. Death rate for patients receiving adjuvant EBRT is 44.95 per 1,000 person-years, while patients who did not receive adjuvant EBRT had a death rate of 40.95 per 1,000 person-years. Patients aged 80 years or older, divorced and separated tend not to receive adjuvant EBRT, while patients with tumor size of 51-100mm and 101-200mm are more likely to receive adjuvant RT. Crude rate ratio among those patients receiving RT compared to the rate of those who did not receive adjuvant RT is 0.91 (95% CI: 0.76-1.07). Adjusting for possible confounders did not change the rate ratio between adjuvant EBRT compared to resection alone. Extent of resection did not modify the effect of adjuvant RT to death (likelihood ratio test-0.363). Survival analysis using Kaplan Meier curve showed no difference whether a patient received adjuvant EBRT or not (log rank test-0.238). Conclusions: There is no clear evidence on the survival benefit for use of adjuvant EBRT in resected atypical meningioma compared resection alone. This is true both in incomplete and completely resected atypical meningiomas.