Non-invasive diagnosis of endometriosis based on a combined analysis of four plasma biomarkers

Purpose: The objective of the current study was to evaluate whether the analysis of different proinflammatory and angiogenesis-regulating cytokines in a well-defined patient population can be accurate for the diagnosis of endometriosis at different stages. Material and methods: For this prospective study, plasma samples were collected from women undergoing laparoscopic surgery for subfertility. The stage of endometriosis was confirmed during laparoscopy. Results: Plasma levels of interleukin 6 (IL-6), carbohydrate antigen (CA)-125 were significantly higher in women with endometriosis compared with controls (46.70 +/- 27.08 vs. 27.08 +/- 16.29, p < 0.05; 49.39 +/- 28.32 vs. 9.78 +/- 3.87, respectively). In women with minimal-mild endometriosis, only the plasma level of IL-6 was increased (56.45 +/- 23.21 vs. 27.08 +/- 16.29 p < 0.05). In women with moderate-severe endometriosis, plasma levels of IL-6 and CA-125 were significantly increased, and those of Epo and tumor necrosis factor a (TNF-alpha) were significantly decreased (44.53 +/- 31.07 vs. 27.08 +/- 16.29, p < 0.05; 57.84 +/- 61.44 +/- 3.87 vs. 9.78 +/- 3.87, p < 0.05; 26.60.2 +/- 10.19 vs. 30.32 +/- 7.94, p < 0.05; 58.61 +/- 7.93 vs. 65.40 +/- 9.86, p < 0.05, respectively). The area under curve (AUC) for Epo, TNF-alpha, IL-6 and CA-125 were 0.280, 0.322, 0.729 and 0.864, respectively. Conclusions: The results of our study show that progression of endometriosis is associated with the elevated level of serum IL-6. Clearly, larger prospective studies are required to determine the diagnostic potential of measuring circulating inflammatory cytokine levels like IL-6 in endometriosis.