USP22 and neoplasm: As to clinicopathological variables, there was a significant difference of USP22 expression in patients categorized according to primary tumor site, tumor size, differentiation, T classification, N classification, M classification, AJCC stage, Ki-67 status, and COX-2 status, which strongly suggesting that USP22 can be used as a marker to classify subsets of OSCC patients with more aggressive disease.