Endometrial cancer drug trial halted early: letrozole shows no clear benefit

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Older than 18 years old; 2. Initial diagnosed with stage I-IV(FIGO2009) endometrial epithelial cancer, regardless of pathological types; 3. Surgery must have included a hysterectomy, bilateral salpingo-oophorectomy and sentinel node biopsy; pelvic lymph node sampling and para-aortic lymph node sampling are optional; 4. Life expectancy of 2 or more years. 5. Confirmed NSMP with intermediate or higher prognostic risk according to post-operative clinical pathological assessment and molecular classification; 1. Intermediate prognostic risk group: * Stage lB endometrioid + Iow-grade\* + LVSI negative or focal * Stage IA endometrioid + high-grade\*+ LVSI negative or focal * Stage IA non-endometrioid (serous, clear cell, undifferentiated carcinoma, carcinosarcoma, mixed) without myometrial invasion 2. High-intermediate prognostic risk group: * Stage I endometrioid + substantial LVSI, regardless of grade and depth of invasion * Stage lB endometrioid high-grade\*, regardless of LVSI status * Stage II 3. High prognostic risk group: * Stage Ill-IVA with no residual disease * Stage I-IVA non-endometrioid (serous, clear cell, undifferentiated carcinoma, carcinosarcoma, mixed) with myometrial invasion, and with no residual disease 4. Advanced Metastatic: * Stage III-IVA with residual disease * Stage IVB Low grade: G1-2; High grade:G3; 6. Received conventional adjuvant therapy after surgery according to the latest version of NCCN or ESGO/ESTRO/ESP guidelines; 7. Patients with residual tumor after surgery (any single site) must have achieved complete response or partial response after post-operative adjuvant therapy; 8. Expected start of letrozole maintenance within 3 months after adjuvant therapy; 9. Adequate organ function as defined by the following criteria: * White blood cell (WBC) ≥ 3000/μL or Absolute neutrophil count (ANC) ≥1500/μL * Platelets ≥100,000/μL * Serum Aspartate transaminase (AST) and/or serum alanine transaminase (ALT) ≤ 2 times upper limit of normal (ULN) * Serum creatinine ≤2 times ULN 10. Karnofsky score ≥60; 11. Eastern Cooperative Oncology Group (ECOG) Performance status ≤2; 12. Ability to take anti-thyroid drugs, calcium, vitamin D or bisphosphonates together. Exclusion Criteria: 1. Endometrial stromal tumor; 2. Recurrent endometrial cancers; 3. Patients with low prognostic risk according to post-operative clinical pathological assessment ( Stage IA endometrioid + low-grade\* +LVSI negative or focal); 4. Patients require no adjuvant therapy after surgery; 5. Negative expression in estrogen receptor or progesterone receptor according to post-operative Immunohistochemistry; 6. Received other adjuvant therapy within 6 months before surgery: including neoadjuvant therapy, hormone therapy, targeted therapy, immunotherapy and biotherapy, etc; 7. Patients with contraindications for letrozole; 8. Patients with other malignant tumors; 9. History of vital organ transplantation; 10. History of immune disease and need to take immunosuppressor; 11. Uncontrolled psychiatric illness or other situations that would limit compliance with study requirements; 12. History of drug abuse; 13. Participated in other clinical trials; 14. No ability or intention to receive letrozole maintenance/sign the consent/obey the study requirements.