Introduction/Background Endometrial cancer (EC) is one of the common female cancers. In India the incidence of EC is low. National cancer registry project (NCRP) estimated 27922 cases of EC in 2022 in India. Mismatch repair (MMR) abnormality and Lynch syndrome (LS) constitute about 3–5 % of all EC. MMR proteins behave as tumour suppressors. Mutations in MMR result in a Micro satellite unstable phenotype known as MMR deficient (MMRd/MSI-H) EC.

Methodology 53 EC cases were studied using MMR expression of MLH-1, MSH-2, MSH-6, and PMS with immunohistochemistry (IHC) and their expression was correlated with the stage & grade of the disease.

Results Of 53 cases, on histology, endometrioid type was found in 42 (79%) patients. 10 (18%) had serous and 1 (1.8%) had clear cell carcinoma. Of the endometrioid (42 cases), 39 (92.8%) presented in stage 1 and 3 (7.14%) in higher stage. Total 22 cases were MMRd and 31 were MMR proficient (MMRp). MMRd status was not associated with a high grade (grade 3). In contrast MMRp was associated with highest tumour grade (clear cell/serous) in 11 cases. Combined loss of MLH1/PMS2 (82%) was most common MMRd pattern. Combined loss of MSH2/MSH6 and isolated loss of MSH1 were seen in 9% each. Age, grade or FIGO stage was not statistically significantly correlated with MMR expression.

Conclusion No significant difference was observed between MMRd rates in Grade 1 & 2 Tumours (MMRd: Grade 1 vs Grade 2: 40.0% vs 60%; p-value = 0.233).

However, MMRd ( MSI-H) status was observed to be higher in patients with Grade 2 Tumours (73%) as compared to those who had Grade 1 (27%) Tumour. Within the limitation of our small sample size, we can conclude that MMRd tumours are low/intermediate grade and present in early stages. However further studies may confirm this correlation.

Disclosures Conflict of Interest Disclosure Statement

The European Society of Gynaecological Oncology requires clear disclosures from all presenters at its annual congress regarding any financial holdings, funding sources, or affiliations that might raise questions of bias or be perceived to have potentially influenced presentation content. Please disclose any financial relationship from the past three years (dating from the month of submission) of any size.

NAME Priyanka Batra ____________________________________________________

Medanta the Medicity, India _______________________________________________

We have no potential conflict of interest to report