Mismatch repair deficiency and abnormal p53 expression has significant predictive value for progesterone resistance and endometrial tumorigenesis in patients with endometrial atypical hyperplasia receiving fertility-preserving treatment

Objective This study aimed to evaluate the prognostic ability of mismatch repair deficiency (MMR-d) and abnormal p53 expression (p53abn) in patients with endometrial atypical hyperplasia (EAH) who underwent fertility-preserving treatment. Methods This retrospective study evaluated 51 patients with EAH who underwent fertility-sparing treatment. Endometrial biopsy specimens obtained before hormone therapy were collected and used for immunohistochemical staining for MMR and p53 proteins. Response, relapse, and progression rates were assessed based on age, body mass index, diabetes, polycystic ovary syndrome, reproductive history, MMR status, and p53 status. Results Overall, 11/51 (21.6%) patients had loss of MMR proteins and 6/51 (11.8%) had p53abn. Patients with MMR-d had lower complete response (CR) rates than those with normal staining patients at 12 months after initial treatment (p = 0.049). Patients with MMR-d had significantly higher relapse rates than those with MMR-p at the 1-year follow-ups after achieving CR (p = 0.035). Moreover, patients with MMR-d had a higher incidence of disease progression at 2, 3, and 4 years after fertility-sparing treatment (p = 0.001, p = 0.01 and p = 0.035, respectively). Patients with p53abn had higher relapse rates than those with p53wt at the 1- and 2-year follow-ups after achieving CR (p = 0.047 and p = 0.036, respectively). Moreover, patients with p53abn had a higher incidence of disease progression at 3 and 4 years after fertility-sparing treatment (p = 0.02 and p = 0.049, respectively). Conclusions EAH patients with MMR-d and p53abn have a significantly higher risk of disease relapse and progression. Thus, MMR-d and p53abn may be used as predictive biomarkers of progestin resistance and endometrial tumorigenesis in EAH.