[Clinical significance of detection of cathepsin X and cystatin C in the sera of patients with lung cancer].

BACKGROUND AND OBJECTIVE

Cathepsin X (Cat X) has been identified as a member of cathepsin family. Studies have shown that Cat X is involved in tumorigenesis and tumor development of various cancers. The aim of this study is to investigate the relationship between the clinicopathological prognosis and the levels of Cat X and cystatin C in the serum of patients with lung cancer.

METHODS

Blood samples were collected from 84 patients with lung cancer and 36 healthy control subjects. Cat X and cystatin C were determined by quantitative ELISA.

RESULTS

Cat X and cystatin C levels were significantly higher in the patients with lung cancer than that in the healthy control subjects (P<0.01). Cat X level was correlated with the pathological types of lung cancer (P=0.076). Cystatin C was positively correlated with TNM stage (P=0.01). Furthermore, cystatin C/Cat X was correlated with lymph node metastasis (P=0.058). The patients with high Cat X levels experienced significantly shorter overall survival rates compared with those with low Cat X. Univariate analysis indicated that Cat X and TNM stage were related to overall survival. Multivariate Cox analysis indicated that TNM stage may be used as an independent prognostic variable in patients with lung cancer.

CONCLUSIONS

Cat X and cystatin C levels were significantly higher in patients with lung cancer. Cat X and cystatin C detection in the sera may contribute to the diagnosis of lung cancer and may be used to evaluate the prognosis of patients with NSCLC.