Serum CD44 levels in patients with non-small cell lung cancer and their relationship with clinicopathological features

Serum CD44 standard and CD44 variant 6 levels were measured in 45 non-small cell lung cancer (NSCLC) patients and 33 patients with benign lung disease by enzyme-linked immunosorbent assay (ELISA). Expression of CD44 variant 6 in trans-bronchial biopsy specimens from the NSCLC patients was studied by an immunoperoxidase method. CD44 standard and CD44 variant 6 levels in NSCLC patients were not significantly different from those in benign lung disease patients. However, serum CD44 variant 6 level in squamous cell carcinoma patients (226.8 +/- 152.7 ng/ml) was significantly higher than in patients with benign lung disease (154.8 +/- 46.4 ng/ml) (P = 0.011). Neither the serum level of CD44 standard nor that of CD44 variant 6 was correlated with disease Stage and metastasis. CD44 variant 6 expression was most frequently observed in squamous cell carcinoma (P = 0.00058); 15 (79%) of 19 squamous cell carcinoma cases were positive, as were five (22%) of 23 adenocarcinoma cases and two (67%) of three large cell carcinoma cases. Serum CD44 variant 6 levels were 217.1 +/- 143.1 and 156.1 +/- 48.8 ng/ml in patients with and without positive expression of CD44 variant 6, respectively (P = 0.020). Serum CD44 standard and CD44 variant 6 levels are not useful indicators of tumor burden and metastasis in patients with NSCLC. CD44 variant 6 expression might be associated with histological features of NSCLC.