Purpose: The aim of this study was to determine whether collagen XVIII expression is correlated with circulating serum endostatin and whether this has any prognostic value in patients with non-small cell lung cancer (NSCLC).
Experimental design: Serum endostatin levels were measured quantitatively by a competitive enzyme immunoassay, and collagen XVIII expression in tumor tissue was investigated with an immunohistochemical method in a series of 94 patients who underwent surgery for NSCLC.
Results: Sixty cases (63.8%) had positive immunohistochemical staining with anticollagen XVIII polyclonal antibodies, including strongly positive staining in 11 (11.7%) cases. The mean (+/- SD) serum endostatin level was 41.6 +/- 34.4 ng/ml in the patient group and 16.3 +/- 10.3 ng/ml in the control group (P < 0.0001). The 11 cases who were strongly collagen XVIII-positive had significantly higher serum endostatin levels than the cases who were negative or weakly positive (P = 0.0297). The 5-year survival rates of negative, weakly positive, and strongly positive patients were 77.8%, 56.9%, and 43.8%, respectively. The cases with strongly positive collagen XVIII expression had a significantly poorer outcome than cases with negative expression (P = 0.0027). A multivariate analysis with Cox proportional hazards model for disease-specific survival revealed that expression of collagen XVIII (strongly positive versus negative; weakly positive versus negative), tumor classification, and regional lymph node classification were independent prognostic factors.
Conclusions: Our results suggest that expression of collagen XVIII in tumor tissue is strongly associated with a poorer outcome in NSCLC and correlates with elevated levels of circulating serum endostatin.