ARID1A and neoplasm: In contrast, in the β -CATabn subgroup, loss/mutation of ARID1A is associated with older age (p = 0.044), high grade (p = 0.001), extensive necrosis (p = 0.019), tumor budding (p = 0.019), high sTILs and iTILs (p = 0.009 and p = 0.012, respectively), high mitotic rate and high Ki-67 proliferative index (p = 0.001 and p = 0.003, respectively).