Proposed reference value of the CA 125 tumour marker in men. Potential applications in clinical practice

CA 125 is a tumour marker usually used to monitor the clinical course of the patients with ovary cancer. The frequently used reference value of this marker is 35 U/mL. However, some arguments to allow us to question us the validity of the classical reference value: i) a second generation of immunoassays, ii) diverse studies related to the factors that influence in the CA 125 serum concentrations and iii) the new applications of CA 125 in pathologies different to the ovary cancer.

1) To propose a reference value of CA 125 in men; 2) To evaluate the CA 125 serum concentration according to different variables, some of which can be altered in pathologies where CA 125 level can be monitored and/ or altered.

65 healthy men were included (age: 40.21+/-10.60 years). A survey containing different parameters and an analytic that contained a hemogram, hepatic, renal, pancreatic profile, ionogram, thyroid function, tumour markers and NT-Pro-BNP was carried out to exclude the presence of a pathological situation. The percentile 95 (P(95)) was calculated to obtain the reference value. Correlations among the CA 125 and the different variables were analyzed by the Spearman test.

The median [ranges] and the P(95) were: 7.50 [3.00-25.00] and 20.17 U/mL, respectively. 78% of the values of CA 125 were < or =10 U/mL, 94% were < or =15 U/mL and 95% were < or =20 U/mL. Furthermore, the studied variables don't seem to influence in the concentrations of this marker.

The proposed reference value obtained in healthy male subjects is significantly lower than the one used in the clinical practice. This value should be kept in mind when extending the use of this marker to other pathologies which was not used up to now.