This study was designed to evaluate selenium, copper, and zinc serum concentration in patients with cancer of the digestive tract before and after treatment with 5-fluorouracil. methotrexate, and L-folinic acid. Also, we evaluated whether any change was correlated with the nutritional status of the patients. Tract elements were measured by atomic absorption spectroscopy. The nutritional status of each patient was assessed through a combination of biohumoral (prealbumin. cholinesterase, cholesterol, transferrin, tot1 proteins, albumin/ globulin ratio, C-reactive protein) and bio-impedance (percent free fat mass, percent fat mass. FFM/FM, percent total body water, extra/intracellular water. Na+/K+ ratio exchange able, body mass index, basal metabolic rate, and phase angle) parameters before and after the chemotherapeutic treatment. Most patients showed significant alteration of the nutritional parameters compared with control (prealbumin, cholinesterase. percent for fat mass, percent fat mass, P < 0.01 versus controls: cholesterol, transferrin P < 0.05 versus controls: total proteins, albumin/globulin ratio P < 0.001 versus controls). However, no significant change of biochemical and bio-impedance parameters was observed at the end of the therapy. Only 4 of the 50 patients showed significant alteration of nutritional indexes after chemotherapy. Selenium and zinc concentration were significantly lower (Se 56.4 +/- 8.4 <mu>g/dL and Zn 79.5 +/- 8.6 mug/dL: P < 0.01, versus controls) whereas copper concentration wax significantly higher (Cu 111.9 +/- 19 <mu>g/dL; P < 0.01) in cancer patients than in control subjects. Moreover, at the end of treatment selenium and zinc serum levels showed a significant decrease compared with base line values (Se 51.4 +/- 7.2 <mu>g/dL and Zn 73.4 +/- 7.4 mug/dL; P < 0.001). Copper concentration at the end of the therapy was higher compared with base line concentration (118.4 +/- <mu>g/dL; P < 0.001). The change in tract element serum concentration at the end of therapy was of the same magnitude in patients who did not show significant change in their nutritional status and in those who did. In conclusion, cancer patients show an alteration in the serum concentration of trace elements. Chemotherapy did not alter the nutritional status of our patients but further modified selenium, zinc, and copper serum levels. This suggests that the alteration of trace elements after polychemotherapy is the consequence of a direct effect of antineoplastic drug on the catabolism of trace elements. J. Trace Elem. Exp. Med. 14:73-79, 2001. (C) 2001 Wiley-Liss, Inc.