Trace element changes in serum and skeletal muscle compared to tumour tissue in sarcoma-bearing rats

Cancer cachexia is characterized by wasting of the lean tissue and profound changes in the body composition of the tumour host. These changes are partly explained by an inefficient energy production but other factors may also be important, such as deficiency of essential nutritional components. In the present study the changes of trace elements in serum and skeletal muscle were compared to those in tumour tissue during tumour progression in sarcoma--bearing rats. Trace element analysis was performed directly on serum specimens and frozen sections from skeletal muscle and tumour tissue. The samples were analysed by energy dispersive X-ray fluorescence spectrometry (EDXRF) without any other pre-treatment such as homogenization and extraction. In skeletal muscle an increased content of zinc was found during tumour progression. The iron concentration was unchanged, but since muscle wasting is part of the cachexia this means that iron was transferred to other compartments. Thus the iron content of serum was doubled and tumour tissue had a high concentration of iron. Selenium was below detection limits in skeletal muscle but well detectable in tumour tissue and it increased during tumour growth. Rubidium and potassium content correlated in all tissues (R:0.98) as did bromine and sodium (R:0.98). Copper behaved differently from the other trace elements and showed large variability. This was also true when tissue copper was individually correlated to all other trace elements in the same tissue.