Trace Elements in Pleural Effusion Correlates with Smokers with Lung Cancer

Smoking leads to the presence of various elements, including toxic metals and metalloids, in tissues and fluids, thus contributing to cancer risk. This study assessed the concentrations of 14 elements (Ag, Al, As, Co, Cr, Cu, Fe, Ni, Mn, Mo, Pb, Sn, V, and Zn) and biochemical parameters (glucose, lactate dehydrogenase, and total protein) in the pleural effusion (PE) of patients with lung cancer. The potential association of these parameters with smoking was assessed. Total of 48 patients with lung cancer (26 non-smokers and 22 smokers) received thoracocentesis for PE removal. Analysis results revealed that among the biochemical parameters, only the glucose concentration was significantly higher in current smokers than in non-smokers; the other parameters showed no significant difference. The concentration of Zn in the PE was significantly lower in all smokers (10 former and 12 current smokers) than in non-smokers, but the other elements did not differ significantly between the two groups and smoker subgroups. Simultaneously, Zn correlated negatively with glucose concentrations in all smokers, positively with lactate dehydrogenase (LDH) concentration in current smoker, and positively with total protein (TP) concentrations in non-smokers. This is for the first time the relation between Zn and certain biochemical parameters in PE was found, the observation requiring further studies to explain the potential interactions between this element and glucose, LDH, and TP concentrations.