Conditional Probability of Survival in Patients with Glioblastoma Multiforme in the Temozolomide Treatment Era

Abstract

Introduction: Glioblastoma multiforme (GBM) is the most aggressive of gliomas. With standard treatment consisting of surgery followed by radiotherapy (RT) with concurrent and adjuvant temozolomide (TMZ), median survival is approximately 14.6 mo. These estimates are not as informative to patients ( pts) who have survived for some time after diagnosis. Aim: To retrospectively review outcomes and report conditional probability estimates in the TMZ treatment era of pts who presented to a multidisciplinary team at the tertiary referral center PrincessMargaretHospital, Toronto, with a diagnosis of GBM. Methods: 892 pts were followed from 01/04 - 08/10. Complete demographics, performance status (PS), GBM localization, extent of surgery, percent receiving RT +/- TMZ, overall survival (OS) and conditional probability were analyzed. Results: The cohort includes 548 (61%) males with median age 62 (5-93). Baseline PS was 0-1 in 600 (67%), 2-3 in 251 (28%) pts. 205 (23%) had frontal lobe tumors. Extent of surgery; 26% biopsy, 68% partial/subtotal resection, 6% unknown. 516 (58%) received concurrent RT/TMZ +/- adjuvant TMZ. Survival was similar for those with frontal lobe tumors vs other locations (10.2 vs 9.7 mo, Logrank test p = 0.28). OS for biopsy pts was 4.5 mo (3.5 - 6.2), and partial/subtotal resection pts; 11.6 mo (10.3 - 12.5) (p < 0.001). OS for pts receiving standard RT/TMZ +/- TMZ was 14.2 mo (13.3 - 15.1). Age and PS were significant prognostic factors for OS (p < 0.001). The OS and conditional probability of survival for entire cohort of 892 pts is detailed in Table. 43 (5%) are still alive, 727 (81%) deceased, status unknown in 122 (14%). (Table Presented) Conclusion: The conditional probability of surviving an additional yr after survival to 2 yrs post diagnosis exceeds the 1 yr survival rate, indicating that the future prognosis of a pt who has survived for 2 yrs may be as good as those recently diagnosed. Conditional probabilities of survival in this general disease population in the era of TMZ therapy may provide more accurate life expectancy predictions for survivors of GBM.