In order to evaluate whether different solid tumors may specifically i
nfluence plasma free amino acid (PFAA) profile, PFAA were analysed in
seventy-four patients with lung (41 patients) and breast cancer (33 pa
tients) and 28 healthy subjects. In lung cancer patients a significant
reduction of gluconeogenic amino acids, threonine, serine, glycine an
d a significant increase of free tryptophan and glutamic acid was foun
d. In breast cancer patients a significant increase of ornithine, glut
amic acid and free tryptophan was found. The comparison of PFAA profil
es between lung and breast cancer suggests that different tumors have
a different influence on the host's PFAA pattern.