Evaluation of expression of CD15 and sCD15 in non-small cell lung cancer

Changes in cell membrane carbohydrate antigens play an important role in metastatic potential associated with carcinogenesis and in prognostic factors. We investigated immunohistochemically the expression of CD15 and sialyl CD15 (sCD15) in lung cancer tissue by using Leu-M1 antibody and MXKM-93 antibody, respectively, and then assessed the relationship between their expression and the patient outcome. Lung cancer tissue expression of CD15 was significantly higher in adenocarcinoma (55.9%) and squamous cell carcinoma (44.7%) than in small cell carcinoma (10%) (p=0.01, p=0.006). Expression of sCD15 was significantly higher in adenocarcinoma (52.9%) than in squamous cell carcinoma (10.5%) or small cell carcinoma (10%) (p<0. 0001, p=0.016). No association was found between CD15 expression and clinical stage, but sCD15 expression increased with clinical stage (stage I+II vs. III+IV: 16.7% vs. 39.6%; p=0.049). Expression of CD15 (1.5%) was significantly lower than expression of sCD15 (12.3%) in normal surrounding tissue. Examination of associations with outcome in NSCLC revealed that expression of sCD15 in resected cases, and expression of CD15 in non-resected cases were significantly correlated with shortening of median survival time (p<0.05). When associations with prognostic factors were assessed by univariate analysis, expression of sCD15 was found to be correlated with distant metastasis, and expression of CD15 with decrease in performance status (PS). In the multivariate analysis by the Cox proportional hazard model, sCD15 and CD15 negativity contributed to longer survival time after PS and clinical stage. The results of a combination assay of CD15 and sCD15 showed that expression of both carbohydrate antigens significantly shortened survival time in both the resected and non-resected group (log-rank test, p<0.05). This combination assay also appeared to be extremely useful in predicting the outcome in all clinical stages of NSCLC.