Introduction/Background The correlation between CA125 and epithelial ovarian cancer and its following is already known. However, the correlation of this tumor antigen and endometrial cancer is still under investigation and there is controversy regarding the cut-off value of Cancer Antigen 125 (CA125).

Methodology A sample of 128 endometrial cancers, surgically staged from 2012 to 2018 in Imam Hossein Hospital were evaluated. According to exclusion criteria, 82 cases were analyzed finally. Receiver Operating Characteristic (ROC) Curve was used to determine the cut-off value of preoperative CA125 for parametrial and cervical stromal involvement.

Results A high preoperative CA125 level was significantly associated with advanced disease stage, cervical stromal invasion, pelvic lymph node metastases and higher grade (p<0/05); for parametrial invasion,it was marginally significant(p=0.058). Although the correlation between CA125 and myometrial /lymphovascular invasions were not statistically significant (P=0/112 & 0/168 respectively). The suitable cut- off for preoperative CA125 in parametrial invasion was 45/5 u/ml (100% sensitivity, 89% specificity, 33/3% Positive Predictive Value, 100% Negative Predictive Value) and for cervical stromal invasion, it was 41/9 u/ml (87/5% sensitivity, 87/8% specificity, 43/75% Positive Predictive Value and 98/48% Negative Predictive Value).

Conclusion If endometrial cancer invades cervical stroma or parametrium, primary surgical treatment may not be the first treatment approach, neoadjuvant chemoradiotherapy and adjuvant extrafascial hysterectomy could be a better approach with better results and fewer complications. Using preoperative CA125 along with physical examination and imaging modalities would be helpful in predicting cervical stromal and parametrial involvements. More investigations are needed to assess an agreed cut-off value for preoperative CA125 and endometrial cancer extension.

Disclosure Nothing to disclose.