Association of mismatch repair deficiency in endometrial cancer with ¹⁸F-FDG PET/CT and clinicopathological features and their prognostic value

Purpose: Identification of the mismatch repair (MMR) deficiency in endometrial cancer (EC) may aid in the screening of patients who may benefit from immunotherapy. Our goal was to investigate the relationship between MMR status and ¹⁸F-FDG PET/CT metabolic parameters and clinicopathological features in patients with EC, as well as to explore their prognostic value.

Methods: This retrospective study included 106 EC patients who were classified as MMR deficient (dMMR) or MMR proficient (pMMR) group based on MMR protein expression status evaluated by immunohistochemistry. Clinicopathological characteristics and PET metabolic parameters were compared between the dMMR and pMMR groups, and their relationships with MMR status and prognosis were evaluated.

Results: Of 106 EC patients, 30 patients (28.1%) had dMMR, while 76 (71.7%) had pMMR. Compared with the pMMR group, the dMMR group showed a lower prevalence of overweight (BMI ≥ 25) (17.2% vs. 43.9%, P = 0.019) and more lymph vascular space invasion (43.3% vs. 21.1%, P = 0.029). Although no relationship between glucometabolism parameters and MMR status was observed in all enrolled patients, higher SUVmax was observed in the endometrioid type of EC with MMR deficiency (P = 0.047). Additionally, SUVmax related to MMR status was found in EC patients with advanced FIGO stage (P = 0.026) or deep myometrial invasion (P = 0.026). Multivariate Cox regression analysis revealed that lymph node metastasis was independently predictive of PFS, while advanced FIGO stage was an independent predictor of OS. No significant association between MMR status and prognosis was found in EC.

Conclusion: Higher SUVmax was associated with MMR deficiency in EC patients with endometrioid type, advanced stage, or deep myometrial invasion, which may be useful for predicting the MMR status and thus aiding in determination of immunotherapy for patients with EC.