p53 Immunohistochemical Staining and TP53 Gene Mutations in Endometrial Cancer: Does Null Pattern Correlate With Prognosis?

Whether immunohistochemistry (IHC) of p53 accurately reflects the TP53 mutational status of endometrial carcinoma (EC) has not yet been established. This study aimed to clarify the relationship between p53 IHC and TP53 mutations in EC and to examine whether p53 IHC can be a more convenient prognostic marker than TP53 mutation in EC. We performed p53 IHC staining of EC samples obtained via surgery and genetic analyses using next-generation sequencing. p53 IHC results showed that of the 101 cases, 71 (70%) were wild-type (WT), 12 (12%) were overexpression (OE), and 18 (18%) were in the null group. Missense mutations were found in 9 cases (47.4%) in OE, 2 (10.5%) in null, and 8 (42.1%) in the WT group. Truncating mutations were found in 1 case (8.3%) in OE, 6 (50%) in null, and 5 (41.7%) in the WT group. The 5-year progression-free survival was 0% in OE, 74.8% in null, and 79.0% in the WT group. In the prognosis for each type of TP53 mutation, the 5-year progression-free survival was missense (32.2%), truncating (65.6%), and WT (79.7%). These survival comparisons showed that the p53 IHC OE had the poorest prognosis. These results suggest that the p53 IHC OE is an independent poor prognostic factor for EC and can be used as a simple and rapid surrogate marker for TP53 mutations. Contrastingly, the complete absence of p53 IHC-the null staining pattern-may not accurately predict a TP53 mutation in EC, and it is necessary to be more careful in making the diagnosis of "abnormal."