Higher importance of interleukin 6 than classic tumor markers (carcinoembryonic antigen and squamous cell cancer antigen) in the diagnosis of esophageal cancer patients.

It has been suggested that interleukin 6 (IL-6) plays a potential role in the growth and progression of tumors, including esophageal cancer (EC). The aim of the study was to compare clinical significance of serum IL-6 with classic tumor markers - carcinoembryonic antigen (CEA) and squamous cell cancer antigen (SCC-Ag) - in EC patients in relation to its histological types - squamous cell carcinoma of esophagus (ESCC) and adenocarcinoma (AD) of esophagus. The study included 53 EC patients and 90 healthy subjects. Serum IL-6 and CEA levels were determined using immunoenzyme assays, while SCC-Ag - chemiluminescent assay. The diagnostic criteria and prognostic values for markers were defined. The levels of all proteins tested in EC, ESCC, and AD were higher than in healthy subjects. The percentage of elevated results was substantially higher for IL-6 (86%) than for CEA (30%) and SCC-Ag (24%) in EC, similarly as in ESCC (87%, 23%, and 33%) and AD (87%, 39%, and 13%, respectively) patients. Concentrations of IL-6 depended on distant metastases and patients' survival in EC and were significantly higher in ESCC patients with more advanced tumor stage and nodal metastases. The IL-6 area under receiver operating characteristic curve (0.92) was larger than for CEA (0.84) and SCC-Ag (0.62) in EC, likewise in ESCC (0.92, 0.87, 0.77) and AD (0.91, 0.79, 0.57, respectively). Our findings indicate better usefulness of IL-6 than classic tumor markers in the diagnosis of EC, especially in patients with ESCC.