Use of personalized molecular biomarkers in the clinical care of adults with glioblastomas

This study was conducted to assess the current pattern of use and the impact of available molecular predictive and prognostic biomarkers on clinical care in patients with glioblastoma (GBM). An online questionnaire consisting of 15 questions about the frequency of use and clinical utility of tissue-based molecular tests was distributed to 1,053 members of the Neuro-Oncology Community in the United States. A total of 320 responses (30.4 %) were collected. 73 respondents who did not see GBM patients were excluded from analysis. MGMT promoter methylation testing (MGMT-meth) was the most commonly requested (37.2; 95 % CI, 31-44), followed by EGFR amplification (22.7; 95 % CI, 18-28), co-deletion of 1p/19q (22.3 %), EGFR expression (21.5 %), P53 mutation (19.8 %), PTEN mutation or deletion (17.4 %), EGFRvIII mutation (12.1 %), IDH1/2 mutation (12.1 %), PDGFR (4.5 %), and PIK3CA (0.8 %). The perceived utility of these studies was variable between participants. A small percentage of respondents felt that any of the studies were always'' or almost always'' helpful in clinical decision making (MGMT-meth 10.9 %; range, 0-13.8 %), but more frequently never'' or almost never'' helpful (MGMT-meth 25.9 %; range, 25-54.7 %). 26.7 % reported not to routinely order any of these studies. Although molecular markers are frequently ordered for patients with GBM, only a minority of clinicians ordering these tests report that the results influence clinical decision-making. Molecular markers that are likely to affect patient care should be ordered with the goal to maximize benefit for patients and to avoid non-actionable results and additional costs.