Nutritional consequences of cancer in man

Pre- and postoperative aminoacidemia in breast cancer: a study vs. matched healthy subjects

Various alterations of aminoacidemia have been described during breast cancer. The aim of this study was first to establish the specific modifications of plasma-free amino acid concentrations by a comparative study of 19 patients with mammary tumors and 18 healthy volunteers, and, second, to determine the evolution of aminoacidemia after surgical tumor removal. Aminoacidemia was determined the day before (D0), and then five days, one month (M1), and six months after surgical removal of the tumor, and a single determination was performed in control subjects. Plasma levels (mumol/L) of serine and glutamate were higher in cancer-bearing women at D0 (respectively, 124 +/- 3 and 68 +/- 7) than in healthy volunteers (respectively, 110 +/- 6 and 48 +/- 5). Surgical tumor removal induced a normalization of aminoacidemia (in mumol/L at D5: serine: 114 +/- 4; at M1: glutamate: 55 +/- 6 Non Significant (NS) from values of healthy subjects). Among the various patterns reported for breast cancer, we confirm one of those described by Cascino in 1995, and we show that these levels revert to normal after tumor surgical removal.

Ornithine alpha-ketoglutarate limits muscle protein breakdown without stimulating tumor growth in rats bearing Yoshida ascites hepatoma

The growth of the Yoshida ascites hepatoma AH130 (YAH) is associated with early wasting, depletion of intracellular amino acid pools, and a pronounced activation of protein degradation in skeletal muscle of the host animal. Ornithine alpha-ketoglutarate (OKG) is used in the treatment of hypercatabolic states, and it has been suggested that it may improve nitrogen balance through repletion of free amino acid pools and suppression of protein catabolism. In cancer, OKG might similarly improve host nutritional status or stimulate tumor growth if its metabolites are limiting for tumor growth. Enteral supplementation with OKG was investigated in Sprague-Dawley rats bearing YAH. Tumor-bearing rats were compared with ad libitum- and pair-fed controls. Rats received OKG (3.4 to 4.0 g/kg body weight/d) or an equal amount of nitrogen as glycine (n = 8 in each group) for 5 days. Tumor implantation decreased cumulative food intake (-40%), host weight (-6%), skeletal muscle weight, and free amino acid levels in muscle and plasma. Muscle protein balance was estimated in vitro; decreased protein synthesis (-30%) and increased proteolysis (+113%) were observed in epitrochlearis muscles (EPI) of YAH-bearing rats compared with control groups. OKG had no effect on the wet weight (10 +/- 1 g) and nitrogen content of the tumor, or on free amino acid levels in the tumor. In tumor-bearing rats, OKG improved muscle protein balance by reducing breakdown by 33% and overall amino acid release of incubated EPI by 46%.

Alterations in serum levels, anti-tumor activity and toxicity of methotrexate in rats after a short period of nutritional depletion

The alterations in serum levels, anti-tumor activity and host toxicity of methotrexate (MTX) were tested in tumor bearing rats following a period of dietary manipulation. A protein deprived (PD) diet or a diet containing a normal protein content (NP) was administered for 5 days and MTX injected intra-peritoneally (i.p.) at the end of the 5 day period. The MTX serum levels were significantly elevated in rats which received the PD diet, as compared to NP dietary rats. This elevation correlated with an enhanced tumor response to MTX administration. In addition, bone marrow toxicity and intestinal tract toxicity, measured with flow cytometry (FCM) of the bone marrow and morphometry of the jejunal mucosa respectively was increased in rats receiving the PD diet. These results indicate that the serum clearance of MTX is delayed in animals suffering from malnutrition, leading to both enhanced tumor response and increased host toxicity.