Coexistent Endometrial and Fallopian Tube Carcinoma: Molecular and Pathological Features for Risk Stratification

Patients with coexistent endometrial and ovarian carcinoma (CEOC) have been shown to have an excellent prognosis if their tumors meet the International Federation of Gynecology and Obstetrics (FIGO) 2023 endometrial carcinoma (EC) stage IA3 criteria. In addition, excluding the intermediate-risk and high-risk molecular subtypes (mismatch repair deficiency, p53 abnormal, and no specific molecular profile- estrogen receptor low/negative) has been recently shown to improve risk stratification in CEOC. In contrast, coexistent EC with fallopian tube (FT) involvement is considered pathological T3/FIGO stage III. Our objective was to assess whether the FIGO 2023 IA3 criteria for CEOC can identify a subset of patients with coexistent EC and FT carcinoma at low risk of recurrence and if incorporation of molecular features can aid in prognostic stratification. An institutional database search was carried out at 2 institutions to identify T3a EC with FT involvement. Cases with nodal, pelvic sidewall, vaginal, parametrial, adnexal soft tissue, or peritoneal involvement or treated with neoadjuvant therapy were excluded. A total of 71 patients were identified. Fourteen carcinomas (14/71, 19.7%) recurred; of these, 85.7% (12/14) were endometrioid FIGO grade 3 or nonendometrioid histotypes, and 85.7% (12/14) had intermediate or adverse molecular features. Eight carcinomas (8/71, 11.3%) met the FT-adapted FIGO 2023 IA3 criteria with no recurrences. Further modifying the criteria by excluding tumors with adverse molecular features while expanding the pathology criteria to include ovarian and/or bilateral adnexal involvement identified 11 of 71 patients (15.5%), none of whom experienced a recurrence. By adapting the FIGO 2023 criteria for low-risk CEOC to assess coexistent EC and FT carcinoma, we identified a subset of patients with excellent outcomes, such that treatment de-escalation could be considered. Furthermore, it may be possible to expand this category of low-risk coexistent EC and FT carcinoma, based on refined molecular/pathological features, so more patients with uterus/adnexa-confined carcinoma and indolent disease behavior can be identified.