Article Text
Abstract
Introduction Despite demonstration of the shared clonal origin of synchronous endometrial and ovarian cancers (SEOC), the definition of SEOC used in clinical practice has been inconsistent. Our aim was to determine if using the WHO2020-recommended/FIGO-2023-definition of stage IA3 SEOC could identify a clinically relevant biologically indolent subset of patients.
Methods Patients with stage IA3 SEOC, or with coexistent organ-confined endometrial and ovarian carcinomas were identified from a cohort of >2500 endometrial carcinomas (2001-2023), with clinicopathological, molecular, and outcome data compared.
Results Multiple differences were demonstrated between patients with stage IA3 SEOC (n=87) and those with coexistent organ-confined endometrial and ovarian carcinomas (n=85), (table 1). 65% of Stage IA3 SEOC were NSMP (10% POLEmut, 25% MMRd, no p53abn) and concordance with ovarian molecular subtype was high (94%). Improved progression-free survival for stage IA3 SEOC was observed (p=0.028)(figure 1) with only 6 (7%) recurrences and 3 (3%) deaths from disease recorded (vs. 20% and 8% in non-FIGO coexistent endometrial and ovarian carcinomas). Of the 6 Stage IA3 with an event (recurrence+/-death) all but one were NSMP (1MMRd), and no patients had L1CAM overexpression, or were ER negative.
Conclusion/Implications FIGO stage IA3 criteria defines a subset of low-risk SEOC that have a very indolent clinical course, behaving like Independent low-risk primary tumours and who are candidates for de-escalation of therapy. More work is needed to see if this low-risk SEOC definition can be safely expanded (e.g. inclusion of bilateral ovarian involvement, POLEmut high grade EC/OC or deep myoinvasion) or refined (e.g.,exclusion of low grade endometrioid p53abn, MMRd).