Summary A disturbed energy balance has been demonstrated in lung cancer patients. Both an enhanced resting energy expenditure (REE) and a decreased energy intake contribute to weight loss. Enhanced systemic levels of inflammatory mediators were found to be related to the enhanced REE in lung cancer. The aim of the present study was to investigate energy metabolism and systemic levels of inflammatory mediators in small-cell lung carcinoma (SCLC) patients before and after treatment with chemotherapy. Hypermetabolism and an enhanced inflammatory response have already been demonstrated in SCLC by our group before. Twelve newly diagnosed SCLC patients were consecutively included in the study. REE was measured by indirect calorimetry and body composition was determined by bioelectrical impedance (BIA) before and 1 month after treatment. To assess the inflammatory state the acute-phase proteins, C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP), both soluble tumour necrosis factor (TNF) receptors, (sTNF-R)-55 and sTNF-R75, and soluble intercellular adhesion molecule (slCAM)-1 were measured in plasma before and 1 month after treatment. CRP was assessed by turbidemetry, whereas the other inflammatory parameters were measured by enzyme-linked immunosorbent assay (ELISA). A significant reduction in REE was found irrespective of therapeutic outcome, whereas body weight and body composition remained stable. The acute-phase proteins CRP and LBP were reduced significantly after treatment with chemotherapy, whereas both sTNF receptors and sICAM-1 remained enhanced. No correlation, however, existed between the decrease in REE and the decrease in the acute-phase proteins. In conclusion, chemotherapeutic treatment attenuates the tumour-related metabolic derangements and acute-phase response.Keywords: small-cell lung cancer; inflammation; resting energy expenditure; weight loss; acute-phase response Weight loss is a frequently occurring problem in lung cancer patients. Severe weight loss (2 10% weight loss) has been found in 30% of patients with newly detected lung cancer (Staal et al, 1994). Both an increased resting energy expenditure (REE) and a decreased energy intake contribute to weight loss in lung cancer patients (Russell et al, 1984;Hansell et al, 1986; Fredrix et al, 1991;Staal et al, 1994). Apart from body composition, the localization of the tumour in the central airways and enhanced systemic levels of inflammatory mediators were found to be determining factors of an increased REE in lung cancer patients (Staal et al, 1994;. The involvement of inflammatory mediators in metabolic derangements has been demonstrated in experimental animal studies as well as in oncological patients with different tumour types (Fong et al, 1989; Denz et al, 1993; Falconer et al, 1994;Staal et al, 1995).In addition to general tumour characteristics, histology has to be considered as a factor related to energy metabolism in lung cancer patients. Lung cancer can be divided into small-cell lung carcinoma (SCLC) and non-small...