Epigenetic silencing of MLH1 in endometrial cancers is associated with larger tumor volume, increased rate of lymph node positivity and reduced recurrence-free survival

•MLH1 methylated endometrial tumors have poor prognostic features including larger size.•Tumor volume and mismatch repair class are associated with lymph node involvement.•Women with MLH1 methylated tumors have reduced recurrence-free survival.•Recurrence rate by MMR class differed dramatically in advanced stage endometrial cancer.•MMR defective tumors with MLH1 methylation may exhibit chemoresistance.