Tumour location influences local cytokine production and host metabolism

To determine whether the location of tumour growth influences host cytokine and metabolic responses, experimental subcutaneous (SQ) and liver (LIV) tumours were compared in Buffalo rats. An LIV tumour that was only 1 +/- 1% (P < 0.05 versus SQ) of body weight produced similar anorexia, weight loss, acute phase response, and systemic cytokine responses as are SQ tumour that was 10 +/- 2% of body weight. Neither tumour-bearing group had abnormal liver function tests or evidence of obstructive biliary pathology. Tumour necrosis factor (TNF) was detected by western analysis in both tumour as well as histologically normal liver remote from the tumour in the LIV group but not in livers of animals in freely fed and SQ groups. The proximity of the tumour to competent tissue macrophage populations, such as hepatic Kupffer cells, may be sufficient to induce cachexia. Hence, tumour location may be as important as tumour burden in determining the host's response to cancer.