Serum-soluble receptor-binding cancer antigen expressed on SiSo cells as a clinical marker in lung cancer.

The aim of this study was to explore the diagnostic value of levels of the serum-soluble receptor-binding cancer antigen expressed on SiSo cells (sRCAS1) expressed in lung cancer patients. Enzyme-linked immunosorbent assay was performed to detect serum sRCAS1 levels in 138 patients with lung cancers of various types and in 40 healthy controls. Our results showed that the patients with lung cancer had higher serum sRCAS1 levels than the controls. As disease stages progressed in lung cancer, serum sRCAS1 levels increased; patients with lymph node and distant metastases had higher levels than those without metastases, regardless of histology, age, and gender. At a cutoff value of 19.2 U/ml, sRCAS1 was 91.3% sensitive and 72.5% specific for lung cancer. In conclusion, these results suggest that sRCAS1 levels could have a clinical value for the diagnosis and management of lung cancer and could be used as a new tumor marker of lung cancer.