Evaluation of p53 protein expression in endometrial carcinoma using immunohistochemistry: A study from Vietnam.

e17614 Background: The International Federation of Gynecology and Obstetrics (FIGO) 2023 recommends integrating molecular subtype evaluation into endometrial carcinoma staging, as it enhances prognostic prediction. Endometrial carcinoma is classified into four molecular subgroups: polymerase-E exonuclease domain-mutant (POLE-mut), mismatch repair-deficient (MMR-d), p53-abnormal (p53-abn), and no specific molecular profile (NSMP). FIGO's updated classification also incorporates histological type, grade, and lympho-vascular space invasion (LVSI) extent for post-operative risk management. Despite these advancements, there is a lack of studies from Vietnam examining this classification. Methods: This study aimed to assess the prevalence of p53-abn endometrial carcinoma and its impact on FIGO staging. We enrolled women with endometrial carcinoma who underwent hysterectomy at HCMC Oncology Hospital from January to December 2023. Immunohistochemistry was used to classify endometrial carcinomas based on p53 expression, dividing patients into p53-abnormal and p53-normal groups for comparative analysis. Staging utilized both FIGO 2009 and FIGO 2023 criteria to identify potential stage shifts. Results: Among the 58 patients included, 17 had pathologically confirmed abnormal p53 expression. Of these 17 patients, six had non-endometrioid carcinoma, seven had grade 3 tumors, and 15 were stage II-IV according to the 2023 revised FIGO staging system. Significant intergroup differences were observed in histological type (75% vs. 22%, p < 0.01), tumor grade (46.7% vs. 11.4%, p = 0.02), and FIGO stage (42.9% vs. 8.7%, p = 0.01). Stage shifts occurred in 14 patients, as all endometrial carcinomas of aggressive types or with substantial LVSI were classified as stage II under the FIGO 2023 system, with 8 patients classified as p53 abnormal. Conclusions: In Vietnam, endometrial carcinoma exhibited a subgroup distribution consistent with previous reports, supporting the 2023 FIGO staging system, which provides improved prognostic accuracy without necessitating molecular subtype evaluation. We recommend implementing this new staging system for endometrial carcinomas and consider molecular evaluations, especially in resource-limited settings.