Prevalence of Mismatch Repair Gene Defects by Means of Immuno-histochemistry Staining for MMR Proteins in Endometrial Cancer

In India, the incidence of uterine cancer is 17,420 per year. Presence of mismatch repair genes is one of the risk factors which can cause microsatellite instability in DNA leading to hereditary syndromes as well as sporadic cancer. In the present study, we aim to determine the prevalence of MMR gene mutations by IHC staining for MMR proteins in endometrial cancer. We further aim to corelate various clinic-pathological features with mismatch repair gene defect (MMRd) cancers and to determine its effects recurrence and survival in endometrial cancer.

This is an ambispective study of a retrospectively selected cohort followed up prospectively. It was conducted in the Department of Gynaecological Oncology, AIMS. The cohort was evaluated for the four MMR proteins via IHC staining, and their various clinic-pathological factors were studied. Also, the factors affecting their recurrence free survival (RFS) and overall survival (OS) were observed.

The prevalence of MMR loss in endometrial cancer patients was 31.34%. Most common loss of MMR gene was MLH1 and PMS 2 (57.14%). We did not find any significant differences pertaining to age, BMI, menstrual status, family history and second malignancies in both groups of endometrial cancers. While comparing the histopathological characteristics, no significant difference was found regarding to histopathology, stage, type, grade, P53 status, tumour size, lymph node involvement and LVSI status. No significant difference was seen between two groups in RFS and OS.

We found a significant proportion of endometrial cancers with defective MMR genes in Indian population. We did not find any correlation of MMR to the various clinical and histopathological factors that we analysed. MMRd did not significantly affect the RFS and OS in endometrial cancers.