Serum interleukin 6 and cancer antigen 125 in the non-invasive diagnosis of endometriosis

Background:

The role of interleukin 6 in endometriosis has been extensively studied but results were inconsistent. The purpose of this study was to determine the performance of serum interleukin 6 and serum cancer antigen 125 for non-invasive diagnosis of endometriosis.

Methods:

In this prospective diagnostic study, 100 reproductive women who underwent laparoscopy were studies. Patients were divided into endometriosis group (n = 60) and control group (n = 40). Blood samples were taken preoperatively for analysis of serum interleukin 6 and cancer antigen 125 levels.

Results:

Level of serum interleukin 6 and cancer antigen 125 in endometriosis group were significantly higher than those in control group (1.93 versus <1.50 pg/mL and 41.85 versus 11.86 IU/mL, respectively). A cutoff level of interleukin 6 at 1.52 pg/mL provided sensitivity of 63.3%, specificity of 55%, positive predictive value of 67.9%, and negative predictive value of 50%. The threshold level of cancer antigen 125 at 31 IU/mL had sensitivity of 70%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 69%. The combined test had sensitivity of 86.7%, specificity of 60%, positive predictive value of 76.5%, and negative predictive value of 75%. The area under receiver operating characteristic curve of serum interleukin 6, cancer antigen 125, and combined test were 0.614, 0.945, and 0.945, respectively.

Conclusion:

Serum interleukin 6 is not suitable to be a candidate of serum marker for the diagnosis of endometriosis. Serum cancer antigen 125 is better than interleukin 6 for detection of endometriosis stage III/IV. Both of them had low performance for diagnostic test in minimal to mild endometriosis. The combined test does not add more benefit than using cancer antigen 125 alone.