Background/aims: A variety of cancer-bearing patients have been shown to have disturbances in carbohydrate, lipid and protein metabolism. The complex of metabolic derangements of protein in cancer patients may be reflected by alteration in the plasma free amino acid profile. In this study, we try to investigate the plasma free amino acid profile in patients with colorectal cancer and liver cirrhosis with hepatocellular carcinoma, which are the most common cancers in Taiwan.
Methodology: Fasting venous blood samples were drawn from sixteen control volunteers and 42 cancer-bearing patients including 14 early stage colorectal cancer patients (Duke A and B), 18 late stage ones (Duke C and D) and 10 liver cirrhotic patients with hepatocellular carcinoma. Seventeen amino acid levels were measured using a Beckman amino acid analyzer.
Results: About one third of early or late colorectal cancer patients had body weight loss more than 10% in half a year and were defined as malnourished. For individual amino acids, in early colorectal cancer patients, the plasma level of most essential amino acids and non-essential amino acids decreased (significantly in Tyr, Ala, Met, Phe and Thr). In late stage colorectal cancer patients and patients with liver cirrhosis with hepatocellular carcinoma, plasma levels of most essential amino acids and non-essential amino acids decreased more obviously. For group amino acids, the plasma levels of essential amino acids, non-essential amino acids, gluconeogenic amino acids and branched-chain amino acids were also lower in the cancer patients than those in control volunteers. The difference was also noticeably significant in patients with late stage colorectal cancer and liver cirrhosis with hepatocellular carcinoma. The plasma free amino acid patterns in colorectal cancer patients are quite different from those in patients with non-gastrointestinal cancer and weight loss. The plasma level of essential amino acids and branched-chain amino acids was not kept within normal range in colorectal cancer patients. Elevation of plasma aromatic amino acids and methionine levels usually observed in liver cirrhotic patients without hepatocellular carcinoma was not apparent in our cirrhotic patients with hepatocellular carcinoma.
Conclusions: The plasma free amino acid patterns in our colorectal cancer patients and cirrhotic patients with hepatocellular carcinoma were rather characteristic. The results will offer useful tools for improving diagnosis and therapy.