Refining Fertility-sparing Treatment in Endometrial Carcinoma Based on Molecular Classification: a Prospective Multicenter Umbrella Clinical Study（FEMUS）
Endometrial cancer (EC) stands among the most common gynecological malignancies in developed countries and regions, with a notable trend toward younger age at onset. Correspondingly, the demand for fertility-sparing treatment (FST) has been increasingly prominent among young EC patients. High-potency progestogens remain the sole therapeutic option recommended by international guidelines for this patient population; however, approximately 30% of patients exhibit no response to such treatment. The concept of EC molecular subtyping, proposed by The Cancer Genome Atlas (TCGA) in 2013, has revolutionized the diagnosis and management of EC. EC subtypes with distinct molecular features demonstrate substantial differences in biological behaviors and responses to pharmacotherapeutic interventions. Nevertheless, the role of molecular subtyping in guiding FST decision-making-both in terms of its applicability and specific mechanisms-remains an unmet research need worldwide. Notably, the POLE-mutant and microsatellite instability-high (MSI-H) subtypes display the highest sensitivity to immune checkpoint inhibitors, underscoring the clinical value of exploring their utility in FST. The no specific molecular profile (NSMP) subtype is sensitive to progestogens but lacks reliable predictive biomarkers-accurate pre-treatment prediction would enable tailored treatment selection, shorten treatment duration, and enhance therapeutic outcomes. In contrast, the p53-abnormal (p53abn) subtype is associated with a poor prognosis, and FST is therefore not recommended for this subgroup. Building on the aforementioned background and our research team's preliminary clinical findings, this project focuses on the field of FST for EC. To address the current challenges-including narrow indications, limited treatment options, suboptimal efficacy, and the absence of precise personalized regimens-we aim to conduct the world's first prospective multicenter umbrella trial based on EC molecular subtyping. Optimal novel diagnostic and therapeutic protocols will be developed for each molecular subtype, with the goals of optimizing existing FST strategies, improving FST efficacy and reproductive outcomes, expanding eligible indications, and providing high-quality clinical evidence for molecular subtype-guided FST in EC, thereby advancing the overall effectiveness of FST for EC patients.
• Age ≥ 18 years and ≤ 45 years;
• Strong willingness to preserve fertility/uterus: Patients who have fertility requirements and insist on preserving fertility; or patients who have no fertility requirements but insist on preserving the uterus;
• Newly diagnosed endometrial cancer: Pathologically diagnosed as endometrial cancer via endometrial biopsy, diagnostic dilation and curettage, or hysteroscopic examination;
• Recurrent patients: Patients with endometrial lesions who received conservative treatment previously and developed recurrent endometrial cancer, with an interval of more than 6 months from the last standardized treatment, or deemed eligible for enrollment by the researcher after evaluation;
• Imaging examinations (including pelvic enhanced MRI, upper abdominal enhanced CT/MRI, chest non-contrast CT, or PET/CT-MR) performed within 2 weeks before enrollment treatment initiation to confirm that the lesions are confined to the uterus without extrauterine involvement; for patients allergic to iodine contrast agents, MRI can be used instead of CT;
• Clear molecular subtypes: POLE-mutant, NSMP (no specific molecular profile), or MSI-H (microsatellite instability-high);
• Provide informed consent and sign the informed consent form;
• Good compliance and follow-up conditions, willing and able to complete scheduled follow-up visits at our hospital;
• No significant abnormalities in major organ functions, with relevant test values meeting the following requirements:White blood cell count ≥ 3×10⁹/L or absolute neutrophil count ≥ 1.5×10⁹/L; Platelet count ≥ 100×10⁹/L; AST and/or ALT \< 2× upper limit of normal (ULN); Serum creatinine \< 2× ULN;
⁃ Karnofsky Performance Status (KPS) score ≥ 90; Eastern Cooperative Oncology Group (ECOG) performance status score of 0-2;
⁃ Concurrent use of thyroid medications, calcium tablets, vitamin D, bisphosphonates, metformin, aspirin, etc., is permitted;
⁃ Multidisciplinary Team (MDT) discussion is required before treatment initiation.
⁃ Additional Targeted Inclusion Criteria Based on Different Molecular Subtypes： 1) POLE-mutant endometrial cancer: Pathologically and radiologically evaluated as FIGO 2023 Stage IA endometrial cancer; 2). dMMR (deficient mismatch repair)/MSI-H endometrial cancer: Pathologically and radiologically evaluated as FIGO 2023 Stage I-II endometrial cancer; Patients with Lynch syndrome may have other Lynch-related tumors in other systems; 3) NSMP endometrial cancer: Pathologically and radiologically evaluated as FIGO 2023 Stage IA1 endometrioid carcinoma; Pathological grade: G1/G2; Lesions confined to the endometrial layer; Immunohistochemistry: ER-positive, L1CAM-negative (\< 10% positive cells).