Introduction/Background Endometriosis-associated ovarian cancers (ENOCs), endometrioid and clear cell, show higher survival rates, younger age and earlier stage at diagnosis compared to high-grade serous cancers. Nevertheless the current patients’ treatment still follows a ’one-size-fits-all’ approach. ENOCs appear to be similar to their endometrial carcinoma (EC) counterpart: the morphologic affinity between ENOCs and endometrioid EC also suggest similarities in the genomic landscape and some data have already shown a correlation with their molecular profiles. Our study aims at confirming these results in our population.

Methodology This is a monocentric retrospective project including patients diagnosed with ENOC from March 2022 to February 2023, who received a broad-spectrum genomic profiling test (FPG500). We extrapolated the alterations of the EC TCGA classifications and, together with results from immunohistochemistry, we defined 4 classes: POLe-mutated, MSI-H/dMMR, p53-mutated, no specific molecular profile (NSMP).

Results We analyzed 43 patients with ENOCs. Patients’ characteristics are reported in table 1. 29 (67.4%) patients were in the NSPM group and 4 (9.3%) were POLe-mutated. P53 mutation was registered in 9 (20.9%) cases but, since 2 of them had also a deficit in the MMR system, only 7 (16.3%) were considered p53-mutated for the classification. We detected 5 (11.6%) dMMR patients who were referred to our Hereditary Cancer Unit; of those, 2 had a concomitant POLe mutation and have been considered POLe-mutated for the classification. A comparison with respect to the frequencies reported in the EC TGCA classification is also shown in table 1.

Conclusion Our results confirmed a similarity between ENOCs and ECs. Further analyses with an adequate follow-up and a larger sample size are needed to confirm the value of those categories and their implications for tailored treatments. Moreover, for patients with MSI-H/dMMR, a cost-effectiveness study could be performed after a faster referral to screenings and interventions for those patients and their families.

Disclosures Dr. Marchetti has the following disclosures: receipt of grants/research supports: AstraZeneca, Pharmamar, GSK, MSD, Menarini; receipt of honoraria or consultation fees: AstraZeneca, Pharmamar.

Prof. Scambia has the following disclosures: receipt of honoraria or consultation fees: Covidien AG, AstraZeneca/MSD; participation in a company sponsored speaker’s bureau: Olympus Europa, Baxter

Healthcare, Intuitive Surgical Inc., GlaxoSmithKline

Prof. Fagotti has the following disclosures: Receipt of grants/research supports: AstraZeneca/MSD

Receipt of honoraria or consultation fees: Johnson & Johnson; participation in a company sponsored speaker’s bureau: Fondazione Internazionale Menarini

Prof Zannoni has the following disclosures: Participation in a company sponsored speaker’s bureau: GlaxoSmithKline