Abstract
BACKGROUND
This study aims to describe real world characteristics and outcomes of newly-diagnosed glioblastoma multiforme (GBM) patients in relationship to O6-methylguanine DNA methyltransferase promoter (MGMT) testing and methylation status, in the US.
METHODS
Patients receiving care for GBM were identified in the US Oncology Network database from 1/1/2013 to 6/30/2018 and followed up to 9/30/2018. Structured data and chart reviews were used to assess demographic and clinical characteristics, treatment patterns, type of surgery, MGMT methylation, and clinical outcomes.
RESULTS
Of 600 patient charts planned for review, 195 have been randomly selected and reviewed thus far. Of these, 165 (84.6%) had surgical resection and 30 (15.4%) had biopsy only. Eighty-eight (45.1%) patients were tested for MGMT status and 107 (54.9%) were not. Of those tested, 33 (37.5%) were methylated, and 45 (51.1%) unmethylated. Median ages in the overall (including tested and untested), methylated and unmethylated cohorts were 63.7, 58.8, and 66.7 years, respectively. Most common first-line (1L) treatment in overall, methylated, and unmethylated cohorts was radiation concurrent with temozolomide received by 86.2%, 93.9%, and 91.1%, respectively. Median duration of 1L treatment in the overall cohort was 15.1 weeks (95% confidence interval [CI]: 11.9, 21.6) and higher in the methylated vs. unmethylated cohort (25.9 [18.1, 34.6] vs. 15.1 [9.3, 23.4] weeks, p=0.0375). Unadjusted median overall survival and progression-free survival in the overall cohort were 11.4 [9.4, 14.0] months and 5.2 [3.9, 5.8] months, and higher in the methylated vs. unmethylated cohort (20.5 [14.9, not realized] vs. 12.2 [7.1, 17.0] months, p=0.0052, and 9.4 [5.6, 14.0] vs. 5.5 [3.3, 6.8], p=0.0092, respectively).
CONCLUSIONS
Fewer than half of GBM patients were tested for MGMT methylation in the US community. Clinical outcomes, while better among patients with methylated MGMT, remain poor and current treatment options are limited.
RTHP-21. CLINICAL OUTCOMES AND PATTERN OF FAILURE IN NEWLY DIAGNOSED GLIOBLASTOMA MULTIFORME TREATED WITH DOSE ESCALATION INTENSITY MODULATED RADIOTHERAPY (IMRT)