Elevated sialyl Lewis X-i antigen levels in pleural effusions in patients with carcinomatous pleuritis.

The levels of sialyl Lewis X-i antigen (SLX), which is one of the cancer-associated carbohydrate antigens, were evaluated in 83 malignant and 46 benign pleural effusions. SLX levels in pleural effusion due to lung adenocarcinoma were significantly higher than those due to benign diseases (p < 0.0001), lung cancer other than adenocarcinoma (p = 0.0052), and adenocarcinoma originating from other organs (p = 0.0492). According to receiver operating characteristic (ROC) curve analysis, the optimal cut-off level in the discrimination between malignant and benign pleural effusions was 92 U/ml, which gave a sensitivity of 57.1% and a specificity of 77.8%. The cut-off level of pleural effusion in patients with carcinomatous pleuritis might be higher than that of serum (38 U/ml).