IDH1 and central nervous system cancer: When compared with the tissue gold standard, the sensitivity for 1p/19q-codeletion is 51% while MGMT methylation status ranges from 50% to 55% with a specificity of 100%.32,33 Boisselier et al detected IDH1 mutation in ctDNA extracted from the serum of patients with glioma with a sensitivity of 60% and specificity of 100%34 (Table 1).