Recurrence-Free Survival in Glioma Patients

Patient characteristics were summarized with frequencies and percentages or medians and ranges, as appropriate. Recurrence-free survival (RFS) was defined as the time from original diagnosis to earliest radiographic evidence of tumor recurrence (defined as the presence of new nodular enhancement in or adjacent to the resection bed after radiographically confirmed GTR), and patients were censored at date of last follow-up or death if they did not have a recurrence. Associations with RFS were assessed with likelihood ratio tests from Cox proportional hazards regression models, and hazard ratios together with 95% confidence intervals were reported. RFS at 5 and 10 years were estimated with the Kaplan-Meier method. The concordance index (c-index) was calculated as a measure of how well each predictor discriminates between those with versus without recurrence. Due to the low number of events (recurrences), no multivariable analysis was performed and no adjustment for multiple testing was performed. P-values less than .05 were considered statistically significant. Analyses were conducted using SAS version 9.4 (SAS Institute Inc.) or R.²¹