Urinary gonadotropin peptide (UGP) and serum CA 125 in gynaecologic practice, a clinical prospective study

Abstract

Background: Beta human chorionic gonadotropin (beta-hCG) is expressed in human fetal tissue and cancer cells of various histologic types. It is degraded to the beta-core fragment (beta cf-hCG) which is concentrated in urine, and is known as urinary gonadotropin peptide (UGP). The objective of this study was to assess 1) the value of urinary gonadotropin peptide (UGP) as a single test and the combination of UGP with CA 125 as a diagnostic test in predicting the benign or malignant origin of gynecologic disease, 2) the influence of surgical removal of the tumor on the levels of UGP and CA 125, 3) the influence of the urinary concentration on the UGP levels in relation to the test results. PATIENTS, MATERIALS, METHODS AND STATISTICS: Serum and urine were collected from 31 gynecological patients with malignant and non-malignant disease, preoperatively, and 1 week and 6 weeks after surgery. Optimal cut-off levels were determined by Receiver Operating Characteristic-curves (ROC). Sensitivity (SENS), specificity (SPEC), positive (PPV) and negative predictive value (NPV) and overall test accuracy (ACC) for their ability to discriminate benign from malignant masses were calculated. Logistic regression analysis was performed to calculate the contribution of CA 125, UGP and UGP/creatinine (UGP/creat) to a model predicting malignancy.

Results: The optimal cut-off level for UGP was found 1 fmol/l, for UGP/creat 1.33 fmol/mg creatinine and for CA 125 100 kU/L. The distribution of the urinary creatinine values varied considerably (median = 8.3 mmol/l, range 0.6-25.8 mmol/l). The correlation coefficient (r) between log UGP and log CA 125 was 0.44 (p = 0.001) and between log UGP/creat and log CA 125 0.53 (p < 0.0001).

Conclusions: UGP may be used as a tumor maker in gynecological disease. However, CA 125 as single test discriminates malignant from benign disease better than UGP or UGP/creat. In a logistic model the combination of CA 125 with UGP and UGP/creat predicts the benign or malignant character in 89% of the study population. Significant changes in UGP and UGP/creat levels were seen after removal of benign tumors, however, this was not found in ovarian cancer patients. Correction of the UGP values for the urinary concentration improved the results slightly.