ELEVATED PLEURAL EFFUSION SCC ANTIGEN CONCENTRATIONS DO NOT PROVE DEFINITELY MALIGNANCY SECONDARY TO METASTATIC SQUAMOUS-CELL CARCINOMA OF THE LUNG

The concentration of SCC antigen was determined in the pleural effusions of 98 patients, including 25 patients with squamous cell carcinoma of the lung, 28 patients with adenocarcinoma of the lung, 4 patients with extrapulmonary tumors, 3 with pleural mesothelioma, and 38 with benign disorders of different origin. SCC antigen was assessed with the SCC-RIA of Abbott (Wiesbaden-Delkenheim). The median value of SCC antigen concentrations was significantly higher in patients with squamous cell carcinoma compared to those of the other groups. The cutoff value for recognizing malignant effusions due to squamous cell carcinoma based on maximal Youden-index was set at 18.1-mu-g/l. SCC antigen was raised in 92% of patients with squamous cell carcinoma, but in only 5.5% of patients of the control groups. By contrast, cytology was only positive in 16% of pleural effusions deriving from patients with squamous cell carcinoma. Thus, elevated SCC antigen concentrations do not prove the diagnosis of malignant pleural effusions due to squamous cell carcinoma.