OVX1 as a marker for early stage endometrial carcinoma

Background. Endometrial carcinoma is generally diagnosed only after the onset of postmenopausal bleeding. Although most patients with Stage I disease can be cured, the prognosis worsens significantly when the tumor is no longer confined to the uterine corpus. Serum CA 125 is elevated in only 10–20% cases of Stage I and II endometrial carcinoma. A serum tumor marker that can detect early stage endometrial cancer might aid in management of the disease. Methods. An OVX1 double‐determinant radioimmunoassay was used to detect an epitope on a high‐molecular‐weight mucinlike glycoprotein found in the sera of 45 patients with endometrial cancer. Results. Apparently healthy persons had serum OVX1 antigen levels of 2.23 plus or minus 2.48 U/ml (mean ± standard deviation). Elevated levels of OVX1 antigen (>7.2 U/ml) were found in 5% of 184 healthy persons and in 64% of 45 patients with endometrial cancer. OVX1 antigen was elevated in 64% of 36 patients with Stage I, 50% of 2 patients with Stage II, 60% of 5 patients with Stage III, and each of 2 patients with Stage IV endometrial cancer, but only 8.6% of 58 patients with endometriosis. Elevation of serum OVX1 was found more frequently in patients with deep myometrial invasion and with poorly differentiated tumors (P < 0.01). Conclusions. The OVX1 antigen deserves further evaluation as a marker for early detection of endometrial cancers and as a prognostic factor for women with apparent early stage disease.