Diagnostic value of serum glutathione peroxidase 3 levels in patients with lung cancer

Background We selected glutathione peroxidase 3 ( GP x3) as a specific candidate that is down regulated in patients with lung cancer. In this study, we examined the diagnostic value of serum GP x3, which is an extracellular protein and readily detectable in blood. Methods We collected serum samples from 342 patients with lung cancer and 126 controls (normal healthy people and patients with benign diseases or other malignancies). We measured serum GP x3 levels using the enzyme‐linked immunosorbent assay. Results Mean serum GP x3 levels were significantly lower in the patient group compared with the control group (10.1 ± 5.0 μg/mL vs. 13.0 ± 5.8 μg/mL, P < 0.001). In addition, mean serum GP x3 levels tended to be lower in the patients without metastasis compared with those with metastasis (9.6 ± 4.5 μg/mL vs. 10.7 ± 5.7 μg/mL, P = 0.051). Furthermore, mean serum GP x3 levels had a significant difference according to initial treatments ( P < 0.001). In other words, mean serum GP x3 levels were significantly lower in the surgery group (8.2 ± 4.1 μg/mL) compared with the concurrent chemoradiotherapy (11.5 ± 4.6 μg/mL, P < 0.001), chemotherapy (10.7 ± 5.6 μg/mL, P < 0.001), and supportive care groups (10.9 ± 4.8 μg/mL, P = 0.002). Conclusion Our results showed that serum GP x3 levels were significantly lower in the patients who underwent surgery, which indicates that the serum may have diagnostic value in patients at an operable stage of lung cancer, rather than those at a locally advanced or metastatic stage.