Whole body protein turnover, synthesis and breakdown in patients with colorectal carcinoma

As a basis for assessing protein metabolism in cancer patients, whole body protein turnover, synthesis and breakdown were measured preoperatively using a constant rate infusion of L-(1-14C) leucine in patients with differing stages of colorectal carcinoma. The levels of protein synthesis and breakdown were correlated with the extent of disease as measured by the percentage incorporation of the labelled amino acid into plasma protein (1) and the subsequent modified Dukes' classification (2). Eleven apyrexial patients were divided into two groups; 6 of whom had normal appetites while 5 were anorectic. Protein synthesis increased with advancement of disease in both groups, as did protein breakdown. Protein synthesis and breakdown were lower in the anorectic group, suggesting some degree of starvation adaptation. All patients were in positive balance, despite anthropometric data to support loss of host body protein. This suggests translocation of protein stores from muscle to areas of more rapid protein synthesis such as tumour. Remodelling of body protein is an important facet of metabolism in cancer patients.