(P037) Analysis of Survival Outcomes in Patients With Multifocal Glioblastoma

Omar H. Gayar, MD, Anant Gopal, PhD, Lisa Scarpace, MS, Steven Kalkanis, MD, Tom Mikkelson, MD, Farzan Siddiqui, MD, PhD; Department of Radiation Oncology, Hermelin Brain Tumor Center, Henry Ford Health System

INTRODUCTION: Glioblastoma multiforme (GBM) is associated with extremely poor prognosis and survival. A small subset of these patients present with more than one focus of disease (multifocal or multicentric). We analyzed survival outcomes in patients with multifocal or multicentric GBM treated at our institution.

METHODS: An institutional review board (IRB)-approved retrospective analysis was performed to study patients with GBM who were noted to have multifocal lesions at initial diagnosis and were treated and followed up at our institution between 2005 and 2014. We reviewed patient gender, age at diagnosis, tumor location(s), extent of surgery, pathologic details, and treatment delivered: radiation therapy (RT) ± chemotherapy (CT). Median survival (MS) was calculated for patients who had at least 6 months of follow-up after completion of RT.

RESULTS: A total of 30 patients with multifocal GBM were treated and had adequate follow-up for analysis; 21 patients (70%) were male, and 9 (30%) were female. Median age at diagnosis was 58 years. Regarding surgery, only 6 patients (20%) had subtotal tumor resection (STR), while 23 (77%) had biopsy. No patients had gross total resection (GTR), and one patient did not have resection or biopsy and was treated with RT. The O(6)-methylguanine-DNA methyltransferase (MGMT) gene was found to be methylated in 9 (30%) and unmethylated in 11 (37%) patients. MGMT gene methylation status was unknown for the remaining 10 (33%) patients. A total of patients (90%) had adjuvant RT; 14 patients (52%) were treated to a dose of 60 Gray (Gy), and 5 (19%) received 40–45 Gy. Three patients did not complete RT due to enrollment in hospice or death. Two patients had stereotactic RT as part of their primary RT. A total of 25 patients (83%) had CT: 23 had concurrent CT with RT, and 13 had adjuvant CT. Also, 26 patients had at least 6 months of follow-up after RT completion. Their overall MS was 10.1 months. MS was 16.6 months for patients who had STR and 5.5 months for patients who had biopsy.

CONCLUSIONS: Median survival of multifocal GBM is incredibly short, even compared with the already short median survival of single-lesion GBM. The majority of our patients had biopsy alone, likely due to the nature of multifocal GBM. This most likely contributes to a worse MS.

Proceedings of the 97th Annual Meeting of the American Radium Society - americanradiumsociety.org