Tissue factor pathway inhibitor 2 as a serum biomarker for endometrial cancer: a single-center retrospective study

Endometrial cancer is the most common gynecological malignancy; however, there is no useful blood diagnostic biomarker. This study aimed to determine the utility of tissue factor pathway inhibitor 2 (TFPI2), a biomarker of ovarian cancer, as a diagnostic marker for endometrial cancer.

We examined serum TFPI2 levels in patients with endometrial cancer (n = 328) compared to those in healthy controls (n = 65) and evaluated the performance of serum TFPI2 levels as a diagnostic marker. We investigated the clinicopathological characteristics of patients with TFPI2-negative and TFPI2-positive endometrial cancer. Using immunohistochemistry (IHC), we examined TFPI2 expression in tumor tissues of 105 patients with type II endometrial carcinoma and evaluated the correlation between serum and tissue TFPI2 positivity.

Patients with endometrial cancer had significantly higher serum TFPI2 levels than controls (196.7 pg/mL vs. 83.3 pg/mL; p < 0.001). The sensitivity and specificity were 54.3% and 95.4%, respectively (cutoff value, 191 pg/mL). Serum TFPI2 levels were significantly elevated along with the stage progression (stage I, 189.6 pg/mL; stage III, 230.9 pg/mL; stage IV, 312.5 pg/mL; p < 0.001). Patients with high-risk histology showed significantly elevated serum TFPI2 levels than those with low-risk histology (220.8 pg/mL vs. 187.7 pg/mL; p < 0.001). The positivity rate for TFPI2 was the highest among tumor markers, including CA125, CA19-9, and CEA. Serum TFPI2 and CA125 levels were almost independent (r = 0.203, p < 0.001), and the combined sensitivity increased to 58.8%. The 5-year survival rate was significantly worse in TFPI2-positive patients (≥ 191 pg/mL, n = 178) than in TFPI2-negative patients (< 191 pg/mL, n = 150) (hazard ratio, 8.22; 95% confidence interval, 2.49-27.1; p < 0.001). TFPI2 immunostaining revealed that 37.1% (39/105) of the samples were positive for TFPI2, with an IHC score of > 0. There was no significant difference in the immunostaining score according to histological type. Serum TFPI2 levels and immunostaining score showed poor agreement (kappa coefficient, -0.039).

The serum TFPI2 level is a promising marker for diagnosing and predicting the prognosis of endometrial cancer. No correlation exists between serum and tissue TFPI2 levels. Further multicenter clinical trials are needed to test the utility of TFPI2 as a diagnostic marker.