Introduction This retrospective study aimed to investigate the correlation between TP53 identified via next-generation sequencing (NGS) and p53 expression in colorectal adenocarcinoma (CRC), as assessed by immunohistochemistry (IHC). Additionally, we characterized p53 IHC staining patterns and sought to determine the optimal threshold for p53 expression as a surrogate for TP53 mutation status. Methods In this retrospective cohort analysis, we included 294 archived surgically resected CRC specimens from patients who did not receive preoperative chemotherapy were analyzed. All data were collected from pathology database and electronic medical records. TP53 mutations were identified using NGS, and p53 expression was evaluated by IHC. The correlation between mutation status and IHC staining patterns was assessed, and sensitivity and specificity were calculated. Results The TP53 mutation rate was 78.2%, comprising missense (68.4%), nonsense (12.4%), frameshift (11.0%), and splice-site (8.3%) mutations. Missense mutations were associated with nuclear p53 staining, while frameshift mutations mostly showed loss of expression. Nonsense and splice-site mutations exhibited diverse patterns, including loss of expression, nuclear staining with/without cytoplasmic staining, or cytoplasmic staining alone. Among cases with loss of p53 expression, the TP53 mutation rate was 88.9%. When the proportion of strong p53-positive cells exceeded 55%, the missense mutation-positivity rate increased significantly (P 55%) correlated closely with TP53 missense mutations, supporting IHC as a reliable surrogate. However, cases showing loss of p53 expression should undergo gene sequencing to confirm mutation status.
Wu et al. (Thu,) studied this question.
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