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JPTM > Ahead-of Print

doi: https://doi.org/10.4132/jptm.2020.06.01    [Epub ahead of print]
Prediction of TP53 mutations by p53 immunohistochemistry and their prognostic significance in gastric cancer
Hye Jung Hwang1 , Soo Kyung Nam1 , Hyunjin Park2 , Yujun Park1 , Jiwon Koh3 , Hee Young Na1 , Yoonjin Kwak3 , Woo Ho Kim3 , Hye Seung Lee1
1Department of Pathology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
2Department of Pathology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
3Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea
Corresponding Author: Hye Seung Lee ,Tel: +82-31-787-7714, Fax: +82-31-787-4012, Email: hye2@snu.ac.kr
Received: March 30, 2020;  Revised: May 22, 2020  Accepted: June 1, 2020.  Published online: July 1, 2020.

Recently, molecular classifications of gastric cancer (GC) have been proposed that include TP53 mutations and their functional activity. We aimed to demonstrate the correlation between p53 immunohistochemistry (IHC) and TP53 mutations as well as their clinicopathological significance in GC.
Deep targeted sequencing was performed using surgical or biopsy specimens from 120 patients with GC. IHC for p53 was performed and interpreted as strong, weak, or negative expression. In 18 cases (15.0%) with discrepant TP53 mutation and p53 IHC results, p53 IHC was repeated.
Strong expression of p53 was associated with TP53 missense mutations, negative expression with other types of mutations, and weak expression with wild-type TP53 (p<.001). The sensitivity for each category was 90.9%, 79.0%, and 80.9%, and the specificity was 95.4%, 88.1%, and 92.3%, respectively. The TNM stage at initial diagnosis exhibited a significant correlation with both TP53 mutation type (p=.004) and p53 expression status (p=.029). The Kaplan-Meier survival analysis for 109 stage II and III GC cases showed that patients with TP53 missense mutations had worse overall survival than those in the wild-type and other mutation groups (p=.028). Strong expression of p53 was also associated with worse overall survival in comparison to negative and weak expression (p=.035).
Results of IHC of the p53 protein may be used as a simple surrogate marker of TP53 mutations. However, negative expression of p53 and other types of mutations of TP53 should be carefully interpreted because of its lower sensitivity and different prognostic implications.
Key Words: Gastric cancer; p53; TP53; Next-generation sequencing; Immunohistochemistry