CA125 reference values change in male and postmenopausal female subjects.

Background: In cancer patients, including women with a diagnosis of ovarian cancer, cancer antigen 125 (CA125) is used to evaluate the presence of peritoneal involvement. The aims of the present study were to assess CA125 reference intervals and reference change values (RCV) in postmenopausal reference women, postmenopausal women breast cancer free, reference men and cancer free men.

Methods: The series consisted of 433 subjects: 105 postmenopausal breast cancer free women and 56 cancer free men in addition to a total of 272 reference subjects (145 postmenopausal women and 127 men). Repeated CA125 measurements were made in a subset of 149 women and 54 men to calculate RCV and index of individuality. Serum CA125 levels were evaluated by a chemiluminescent assay.

Results: In postmenopausal reference women, the mean CA125 value and 2.5th-97.5th percentiles were 6.70, 2.60-11.00 kU/L, respectively, with a unidirectional RCV of 38.4%. In postmenopausal breast cancer free women, the mean CA125 value and 2.5th-97.5th percentile were 7.45, 4.09-10.92 kU/L, respectively, with a RCV of 34.5%. The difference between the means was statistically significant (t=-3.02, p=0.003). In the two male subgroups, the difference between the means for CA125 was not statistically significant (t=0.43, p=0.665). On considering the entire male population, the mean CA125 value and 2.5th-97.5th percentiles were 7.50 and 2.40-13.2 kU/L, respectively, while the unidirectional RCV was 34.3%. In all the studied groups, the indices of individuality were equal to or below 0.6.

Conclusions: The extremely low index of individuality found underlines the importance of using the RCV instead of absolute values as a parameter when interpreting the CA125 data in the monitoring and follow-up of patients with ovarian cancer.