ARID1A and neoplasm: In a study that included 1540 patients and nine different tumor types, each with a prevalence of ARID1A alterations of at least 5%, the percentages of patients with microsatellite instability (MSI)‐high and TMB‐high (≥ 20 mutations/mb) were significantly higher in tumors harboring ARID1A alterations than in those with wild‐type ARID1A (20% vs. 0.9%; p < 0.001 and 26% vs. 8.4%; p < 0.001, respectively) [44].