Correlation between P53 immunohistochemical staining and <i>TP53</i> molecular testing in endometrial carcinomas: a detailed assessment of discrepant cases with implications for patient management

Our study demonstrated a good overall concordance between p53 immunohistochemical staining and TP53 molecular results. The concordance can be increased by reviewing the p53 stained slides in discrepant cases but there remains a small cohort of cases, mostly low-grade endometrioid carcinomas (POLE wild-type/MMR proficient), where TP53 mutations are present on NGS but p53 immunohistochemistry is wild-type. Such cases present a dilemma for the pathologist (which TCGA group should they be placed into) and the clinician (should adjuvant therapy be instigated based on the presence of a TP53 mutation alone with no other adverse features). For now, we advise classifying such cases as p53abn but not to administer adjuvant therapy based on the presence of a TP53 mutation alone without other adverse pathological factors. The significance of TP53 mutations in such cases should be determined by larger studies with long-term follow-up.