Metabolic abnormalities in cancer patients: carbohydrate metabolism

The Dichotomous Effect of Thiamine Supplementation on Tumorigenesis: A Systematic Review

The malignant neoplastic cell is characterized by its diverse metabolic changes. It occurs in order to maintain the high rate of proliferation. The possibility of new pharmacological targets has inserted tumor metabolism as a target for recent research, emphasizing the enzymatic activity of thiamin. This review aims to elucidate the behavior of thiamin against tumor development. This is a systematic review in which studies indexed in Pubmed, Scopus, SciELO and BVS were searched using the descriptors (Thiamin OR Vitamin B1) AND (Cancer OR Malignant neoplasia) AND (Tumor metabolism). Title and abstract were read. Duplicates, literary reviews, books, conference abstracts, editorials, and papers published prior to 2010 were eliminated. 23 records were included in this review. Low doses of thiamin have been shown to be enough to stimulate tumor growth. Another population studies has shown evidence of tumor regression after correction of vitamin B1 deficiency. There is an open path for the development of new research to better assess the influence of thiamin on cancer cells. Once the connections between thiamin and the metabolism of cancer cells are fully established, new opportunities for therapeutic intervention and dietary modification will appear to reduce the progression of the disease in patients with cancer.

The red distribution width and the platelet distribution width as prognostic predictors in gastric cancer

Background

Increasing attention is focused on the relationship of inflammation biomarkers with malignant tumors. The purpose of the present study was to detect whether the preoperative the red distribution width (RDW) and the platelet distribution width (PDW) can be used to distinguish patients with gastric cancer (GC) or early stage GC from the healthy controls and predict the progression and prognosis of the GC.

Methods

The RDW and PDW values of 227 patients with GC and 164 patients with early GC were retrospectively analyzed comparing with 101 healthy controls. In addition, the clinicopathological features, survival curves and prognosis of the patients with GC were compared between the high and low groups according to the RDW and PDW values.

Results

Significant higher RDW and lower PDW were detected in patients with GC and early GC compared to the healthy controls. A higher RDW was significantly associated with older age, a larger tumor diameter, deeper tumor infiltration, and lymph node metastasis while a lower PDW was significantly associated with male, older age, a larger tumor diameter, deeper tumor infiltration, elevated CEA and CA125. Increased RDW was significantly associated with worse overall survival (OS) and disease-free survival (DFS) for GC (P = 0.042 and P = 0.033, respectively) and early GC (P = 0.037 and P = 0.009, respectively) while decreased PDW indicated a significantly association with poor DFS for early GC (P = 0.006). Univariate and multivariate survival analysis showed that RDW and PDW can act as independent prognostic factors for DFS (P = 0.028 and P = 0.020) in patients with early GC.

Conclusion

The preoperative RDW and PDW were simple and convenient predictive factors for the progression and prognosis of patients with GC.

Preoperative blood-routine markers and prognosis of esophageal squamous cell carcinoma: The Fujian prospective investigation of cancer (FIESTA) study

This prospective study was designed to investigate the prognosis of preoperative blood-routine markers for esophageal cancer mortality by using data from the ongoing Fujian prospective investigation of cancer (FIESTA) study. Patients who received three-field lymphadenectomy for esophageal cancer between 2000 and 2010 were enrolled. Of 2535 patients with complete survival data, esophageal squamous cell carcinoma (ESCC) accounted for 94.5% (n = 2396). Here, only ESCC patients were analyzed, with the median follow-up time of 38.2 months (range: 0.5 to 180 months). Of 10 blood-routine markers evaluated, platelet count and red cell distribution width (RDW) were two significant predictors for ESCC mortality in men (adjusted hazard ratio or HR = 1.25 and 0.84, 95% confidence interval or CI: 1.08-1.22 and 0.75-0.93, P < 0.001 and P = 0.001, respectively), while in women only lymphocyte showed marginal significance. Based on individual results, a new derivate calculated as platelet count to RDW ratio (PRR) was created, and it was superior over other widely-evaluated derivates in men after adjustment (HR = 1.21, 95% CI: 1.13-1.30, P < 0.001), while there was no observable significance in women. In further stratified analyses, the prognosis of PRR for ESCC mortality was reinforced in men with tumor-node-metastasis stage III (HR, 95% CI, P: 1.18, 1.09-1.28, 0.001), invasion depth T3-T4 (1.17, 1.08-1.26, <0.001) or positive lymph node metastasis (1.37, 1.18-1.59, <0.001). Taken together, we created a new derivate PRR that was proven to be superior over other blood-routine markers and exhibited strong prognostic capability for ESCC mortality in Chinese men.

Alterations in carbohydrate metabolism in cirrhotic patients before and after liver transplant

AIM

The main objective of this study is to demonstrate whether carbohydrate metabolism alterations identified in patients with advanced cirrhosis show any improvement after liver transplant.

METHODS

The study included 86 patients who underwent liver transplant between March 2010 and February 2011. An oral glucose tolerance test was performed before the liver transplant, and 6 and 12 months after. Beta cell function and insulin resistance were also calculated, applying formulae that use basal plasma glycaemia and insulin, and plasma glycaemia and insulin during an oral glucose tolerance test. Risk factors for pre- and post-transplant diabetes were also studied. The diagnosis of diabetes was based on an OGTT.

RESULTS

The proportion of patients with diabetes before transplant, and at month 6 and 12 after transplant were 70.9%, 48.8% and 39.2%, respectively. Compared to baseline, at month 6 the odds ratio of having diabetes was 0.39 (IC 95% [0.21, 0.73]) and at month 12 it was 0.26 (IC 95% [0.14, 0.50]). The composite insulin sensitivity index values at 6 and 12 months were 1.72 units higher (IC 95% [0.84, 2.58]) and 1.58 units higher (IC 95% [0.68, 2.44)] than baseline. A statistically significant association was found between high MELD values and high body mass index, and risk of pre-transplant diabetes (p=0.001 and p=0.033, respectively). Cirrhosis aetiology did not influence the risk of diabetes.

CONCLUSIONS

In this study, we were able to ascertain that alterations in carbohydrate metabolism typical of advanced cirrhosis improve after liver transplant. This improvement is mainly due to an improvement in insulin resistance.

Current therapies in exotic animal oncology

The majority of information on oncology therapies has been reported in humans, canine, and feline patients, and laboratory animals with experimentally induced tumors. A variety of treatments,including radiation therapy, chemotherapy, photodynamic therapy, and others have been used with exotic animals. There are many species of exotic pets, and anatomic differences, as well as husbandry and nutritional requirements, must be taken into account to provide optimal care. By providing a broad overview of therapies and considerations for treatment, this article is intended to provide the practitioner with an overview of approach and options when addressing oncology cases in exotic animals.

Alterations in glucose metabolism associated with liver cirrhosis persist in the clinically stable long-term course after liver transplantation

With increasing long-term survival rates after orthotopic liver transplantation (OLT), metabolic alterations complicating the clinical course, such as diabetes mellitus (DM), become increasingly important. Liver cirrhosis is associated with severe alterations in glucose metabolism. However, it is currently unclear whether these changes are reversed by successful OLT. We therefore characterized glucose metabolism in patients with liver cirrhosis and normal fasting glucose levels before OLT (cir), in the clinically stable long-term course after OLT (OLT), and control subjects (con) using oral glucose tolerance tests (cir = 100, OLT = 62, con = 32), euglycemic-hyperinsulinemic clamps (cir = 10, OLT = 27, con = 14), and positron emission tomography (PET) scan analysis with 18F-fluorodeoxyglucose (FDG) as a tracer (cir = 7, OLT = 7, con = 5). Fasting insulin and C-peptide levels were significantly elevated in patients with liver cirrhosis compared with both control subjects (P <.001) and patients after OLT (P <.001). After OLT, insulin was normalized, whereas C-peptide remained elevated (P < 0.01). In the patients with liver cirrhosis, 27% had a normal glucose tolerance, 38% had an impaired glucose tolerance (IGT), and 35% were diabetic. After OLT, 34% had a normal glucose tolerance, 29% an IGT, and 37% were diabetic. Comparison of the same patients before and after OLT demonstrated that IGT or diabetes before OLT was the major risk factor for these conditions after OLT, which was independent of either immunosuppression (cyclosporine vs FK506) or low-dose prednisolone. Total glucose uptake was reduced in patients with liver cirrhosis to less than half the values in control subjects (21.2 +/- 2.8 vs 43.7 +/- 2.4 micromol/kg/minute, respectively, P <.001), whereas patients after OLT showed intermediate values (35.7 +/- 1.4 micromol/kg/minute, P < 0.05 vs con, P < 0.01 vs cir). This difference was caused by a reduction in nonoxidative glucose metabolism in patients with liver cirrhosis compared with control subjects (7.4 +/- 1.9 vs 28.7 +/- 1.8 micromol/kg/minute, respectively, P <.01) and patients after OLT (20.1 +/- 1.4 micromol/kg/minute, P < 0.05 vs con and OLT). In the PET study, skeletal muscle glucose uptake was significantly reduced in patients with liver cirrhosis compared with control subjects (3.5 +/- 0.4 vs 11.8 +/- 2.5 micromol/100g/minute, respectively, P <.05). After OLT, muscle glucose uptake improved compared with patients with liver cirrhosis (5.9 +/- 1.0 micromol/100g/minute, P <.05) but remained significantly lower than in control subjects (P <.05). In conclusion, these results demonstrate that preexisting IGT or diabetes are the major risk factors for IGT and diabetes after OLT. This finding was independent of the immunosuppressive medication. The peripheral insulin resistance in cirrhosis is characterized by a decrease in nonoxidative glucose disposal that is improved, but not normalized, after OLT.

Integrated analysis of glucose, lipid, and urea metabolism in patients with bladder cancer. Impact of tumor stage

OBJECTIVE

The aim of the study was to characterize the metabolic changes in non-weight-losing patients with cancer of the bladder and to investigate the effect of tumor stage. The kinetics of glucose, glycerol, and urea metabolism were assessed in 22 weight-stable patients with non-metastatic bladder cancer (tumor stage p </= T2, n = 8; tumor stage p > T2, n = 14) and 10 patients with benign uterine myoma (controls).

METHODS

The kinetics of glucose, glycerol, and urea metabolism were assessed by [6,6-(2)H(2)]glucose, [1,1,2,3,3-(2)H(5)]glycerol, and [(15)N(2)]urea. Plasma concentrations of glucose, glycerol, urea, lactate, free fatty acids, insulin, glucagon, cortisol, epinephrine, and norepinephrine also were determined.

RESULTS

Plasma concentrations of glucose, urea, and insulin were higher in cancer patients than in controls (P < 0.05). Whereas glucose production was similar in both groups, glucose clearance was lower in patients with bladder cancer (P < 0.05). Glycerol turnover rate was comparable between groups. Whole-body urea synthesis rate was higher in the cancer group than in the control group (P < 0.05), but there was no difference in urea synthesis when calculated per kilogram of fat-free body mass. Plasma concentrations of glycerol, lactate, free fatty acids, glucagon, cortisol, epinephrine, and norepinephrine were similar in both groups. There was no difference in any parameter between patients with an early tumor stage (p < T2) and patients with a later tumor stage (p > T2).

CONCLUSION

Patients with bladder cancer had a lower rate of glucose clearance than did control subjects. Lipid metabolism was not affected, whereas urea synthesis rate was elevated in cancer patients. However, when expressed per kilogram of fat-free body mass, no difference in protein breakdown could be observed. The tumor stage had no effect on glucose, lipid, or protein metabolism.

Paraneoplastic syndromes

The importance of paraneoplastic syndromes is often underestimated in the horse. Clinically, paraneoplastic syndromes can cause greater morbidity than the actual physical presence of the malignant tumor. The appearance may be the first sign of a malignancy and may be so severe that appropriate therapy for the underlying cancer is not initiated. This article reviews some of the most common paraneoplastic syndromes that are likely to occur in the horse.

Interventional nutrition for the cancer patient

Dogs and cats with cancer have significant alterations in carbohydrate, protein, and fat metabolism, which can result in cancer cachexia and subsequently can decrease quality of life, reduce response to therapy, and shorten survival time. Nutritional modulation may be beneficial in the treatment of cancer patients to reverse these metabolic alterations. There is evidence that foods relatively low in simple carbohydrates with moderate amounts of high-quality protein, fiber, and fat (especially fats of the omega-3 fatty acid series) are beneficial for pets with cancer. In addition, certain supplemental nutrients may have potential to reduce the risk of developing cancer, or the growth and metastases of established malignant disease. Nutritional intervention can be a powerful tool for controlling malignant disease and for reducing toxicity associated with chemotherapy and radiation therapy.

Nutritional and immunologic evaluation of patients with gastric cancer before and after surgery

The main objective was to evaluate a patient's immunologic and nutritional status as a prognostic indicator of morbidity and mortality in patients with gastric cancer. A prospective clinical study carried out at the National Cancer Institute in Bogotá, Colombia. Our study group consisted of 40 patients with a diagnosis of gastric adenocarcinoma that was treated surgically. Blood samples were taken before and 5 d after surgery; mononuclear cell typing was done by flow cytometry allowing a bicolor analysis. Nutritional evaluation was obtained through measurement of albumin levels, average weight loss, and nutritional risk index (NRI). Half of the malignancies were localized to the middle and lower third of the stomach: stage I, 17.55%; stage II, 10%; stage III, 55%; and stage IV, 17.5%. Twenty subtotal gastrectomies, 11 total gastrectomies, 7 gastrojejunostomies, and 2 esophagogastrectomies with D1 and D2-D3 lymph node resection were performed. A postoperative morbidity of 22.5% and a mortality of 7.5% were observed. A preoperative cellular immunosuppression was identified, with a helper lymphocyte (CD4) to suppressor/cytotoxic lymphocyte (CD8) ratio of 1.38 normal value (NV > 1.5), which increased according to the stage of the disease. Patients who died presented with a significantly greater preoperative cellular immunosuppression than those who survived (P = 0.05). Postoperative mortality correlated significantly with hypoalbuminemia (P = 0.008). In those who died, weight loss was greater than in those who survived (P = 0.06). Patients with severe malnutrition had greater postoperative mortality according to the NRI. Severe preoperative cellular immunosuppression (CD4/CD8 < 1), hypoalbuminemia, weight loss, and severe NRI have a positive predictive value for mortality in patients with gastric cancer.

Alterations in lipoprotein profiles in dogs with lymphoma

After a 12-hour fast, blood samples were obtained from 31 dogs with previously untreated lymphoma. Blood samples were also collected from 16 of these dogs after up to 5 treatments with doxorubicin (30 mg/m2 intravenously every 3 weeks). All 16 dogs underwent complete remission. Five dogs were re-evaluated after relapse and after overt signs of cancer cachexia had become clinically apparent. Samples were assayed for 8 quantitative parameters: total cholesterol (T-CH) and total triglyceride (T-TG) concentrations, and the concentration of cholesterol and triglyceride in each of the three major lipoprotein fractions, very-low-density lipoprotein (LDL-CH and LDL-TG), and high-density lipoprotein (HDL-CH and HDL-TG). The results were compared with those from 20 healthy control dogs of similar weight and age before and 3 weeks after being given one dose of doxorubicin (30 mg/m2 intravenously). The administration of doxorubicin to control dogs resulted in a significant (P < .05) decrease in T-CH, LDL-CH, and HDL-CH, as well as a significant increase in VLDL-TG and HDL-TG. When compared with untreated controls, untreated dogs with lymphoma had significantly higher concentrations of VLDL-CH, T-TG, VLDL-TG, LDL-TG, and HDL-TG, and significantly lower concentrations of HDL-CH. HDL-TG and VLDL-TG concentrations from dogs with lymphoma were significantly increased above pretreatment values after relapse and development of overt signs of cancer cachexia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of protein-calorie malnutrition on methotrexate pharmacokinetics

Methotrexate toxicity is increased in protein-calorie malnutrition. The influence of protein-calorie malnutrition on the pharmacokinetics and binding of methotrexate (MTX) and the formation of its major hepatic metabolite, 7-hydroxy-methotrexate was examined in 30 adult, female Lewis rats. Animals were randomized to receive either a standard diet (22.0% protein; 4.20 kcal/g) or a protein-depleted diet (PD) (0.03% protein; 4.27 kcal/g) ad libitum for 35 days. Animals were then separated into two groups for either methotrexate pharmacokinetics (n = 20) or serum protein binding (n = 10) studies. The mean weight loss in the PD group was 26% of their initial body weight, as compared with a 29% weight gain in the control group. In the protein binding study, a significant decrease in serum albumin (19%), uncorrected creatinine clearance (38%), and free fraction of MTX (15%) was found in the PD group. All animals in the pharmacokinetic study received a single intraperitoneal injection of MTX (10 mg/kg), and serum MTX and 7-hydroxy-methotrexate concentrations were determined using a specific, reversed phase, high-performance liquid chromatography assay. The mean AUC0-3 in the PD group was 43.6 +/- 3.9 micrograms/mL per hour compared with 15.8 +/- 1.1 micrograms/mL per hour in the control group (p < .001). The time to peak and the peak serum concentrations were significantly greater in the PD animals, which indicated delayed absorption and clearance. These results suggest that the increase in MTX toxicity observed in protein-calorie malnutrition is associated with a decrease in MTX clearance, and is not related to changes in protein binding or formation of 7-hydroxy-methotrexate.

Glucose-induced thermogenesis in patients with small cell lung carcinoma. Before and after inhibition of tumour growth by chemotherapy

Seven weight-losing patients with histologically verified small cell lung carcinoma were given an oral glucose load of 75 g before and at least 3 weeks after the end of chemotherapy to examine the effect of glucose on whole body and skeletal muscle thermogenesis before and after reduction of tumour. Whole body energy expenditure was measured by the open circuit ventilated hood system. Forearm blood flow was measured by venous-occlusion strain-gauge plethysmography. The uptake of oxygen in skeletal muscle was calculated as the product of the forearm blood flow and the difference in a-v oxygen concentration. Whole body resting energy expenditure (REE) did not increase, it was 4.4 +/- 0.3 kJ min-1 (mean +/- SE) before chemotherapy and 4.4 +/- 0.2 kJ min-1 after chemotherapy. The glucose-induced thermogenesis in the 180 min following the glucose load was 93.6 +/- 9.9 kJ 180 min-1 before chemotherapy. This is significantly increased compared to that found in a healthy control group (74.7 +/- 4.8 kJ 180 min-1, P < 0.02). The glucose-induced thermogenesis was significantly reduced to 47.7 +/- 10.2 kJ 180 min-1 (P < 0.05) after chemotherapy. The oxygen uptake in resting skeletal muscles was 6.9 +/- 0.3 mumol 100 g-1 min-1 before chemotherapy and 7.0 +/- 0.7 mumol 100 g-1 min-1 after chemotherapy. This did not increase during the first 90 min following the glucose load in either investigations. In the period 90-180 min following the glucose load, the oxygen uptake was significantly increased before chemotherapy as compared to after chemotherapy, which suggests that the reduced whole body thermogenesis after chemotherapy in part was due to reduced skeletal muscle thermogenesis.

Energy expenditure in dogs with lymphoma fed two specialized diets

BACKGROUND

Cancer-caused cachexia has been reported to be caused in part by an increase in energy expenditure, and diets with nutrient profiles containing 30-50% nonprotein calories as fat instead of carbohydrate may exacerbate this state of inefficient energy utilization.

METHODS

Indirect calorimetry was performed on 22 dogs with high-grade lymphoblastic lymphoma that were randomized into a blind study and fed isocaloric amounts of a high-fat diet (Diet A) or a high-carbohydrate diet (Diet B) before and after remission was attained with up to five doses of doxorubicin chemotherapy (30 mg/m2 intravenously). Indirect calorimetry was also performed on 30 normal dogs for comparison.

RESULTS

During the initial evaluation period, the resting energy expenditure (REE/kg0.75, P < 0.05) and respiratory quotient (RQ, P < 0.05) were significantly lower than in the controls. Six weeks after the start of the study, the REE/kg0.75 and oxygen consumption (VO2/kg0.75) were significantly (P < 0.05) lower in both groups of dogs with lymphoma compared with the controls. The RQ determined 6 weeks after the start of the study for the dogs fed Diet A was significantly (P < 0.05) lower compared with that in the controls evaluated at the same time. When the two groups of dogs with lymphoma were compared with each other, there was no significant difference in any of the outcomes. The REE/kg0.75 and VO2/kg0.75 values were significantly lower (P < 0.05) in the group fed Diet A after the third evaluation period compared with the second evaluation. The REE/kg0.75 and VO2/kg0.75 values were significantly lower (P < 0.05) in the group given Diet B at the fourth evaluation period compared with the fifth.

CONCLUSIONS

These data suggest that energy expenditure of dogs with lymphoma decreases transiently in response to chemotherapy and remission, but these values are less than those determined in normal dogs and not altered significantly by diet.

Hormonal and metabolic abnormalities in the malnourished cancer patient: effects on host-tumor interaction

Many common metastatic cancers are associated with marked weight loss at the time of diagnosis. Anorexia clearly plays a major role in weight loss in the cancer patient, but cannot explain all of the weight loss noted. Malnourished patients with localized cancers under metabolic ward conditions fail to gain weight when given apparently adequate calories for anabolism, thus suggesting that these patients are hypermetabolic. Increased whole body protein breakdown, increased lipolysis, and increased gluconeogenesis have been repeatedly demonstrated in malnourished cancer patients. Protein and glucose metabolism are closely linked, and both are regulated by a number of the same hormones and metabolites. For example, when increased glucose production in malnourished cancer patients is inhibited pharmacologically, protein catabolism is proportionally decreased. Studies of glucose, growth hormone, cortisol, and insulin secretion following an oral glucose load in well-nourished cancer patients are consistent with insulin resistance but no other hormonal abnormalities. Malnourished cancer patients have elevated levels of growth hormone that are further stimulated by arginine and insulin infusion. No abnormalities of thyroid function were noted in cancer patients. Current studies are underway to determine the mechanisms and effects of progestational steroids and cytokines on both food intake and intermediary lipid metabolism.

The effect of insulin on glucose and protein metabolism in the forearm of cancer patients

This study was designed to study the effect of systemic hyperinsulinaemia (INS) on glucose and protein metabolism in cancer patients. Sixteen cancer patients (8 > 10% weight loss (WL); 8 < 10% weight loss (NWL)) were compared with 12 healthy controls. Glucose uptake (GU) and phenylalanine (PHE) exchange kinetics were measured across the forearm in the postabsorptive state (PA) and in response to INS (71 +/- 5 microU ml-1). At steady state in response to INS, the negative PA PHE net balance became significantly positive, and GU significantly increased, for cancer and control groups, with no significant differences between the two groups. Subset analysis of NWL cancer vs. WL cancer found no difference between WL and NWL for the change in PHE balance from PA and INS, however GU increased significantly only for the NWL group between PA and INS. These data indicate that cancer patients are not resistant to the anabolic effect of INS on protein metabolism, regardless of weight loss, but are resistant to the effect of INS on glucose metabolism when further along in the disease process as evident by more significant weight loss. This differential response to the effect of INS can be exploited in an attempt to promote protein accrual in weight-losing cancer patients.

Cytochrome c oxidase and purine nucleotides in skeletal muscle in tumour-bearing exercising rats

We have previously shown that spontaneous physical exercise can delay the onset of experimental anorexia and cachexia and retard tumour growth and we now report the effects on the energy metabolism in skeletal muscle. Exercising tumour-bearing animals (TBE) had an increased maximal capacity for oxygen uptake expressed as Vmax of the cytochrome c oxidase compared with their tumour-bearing sedentary controls (TBS) [mean (S.E.) 289.9 (30.7) vs. 141.6 (11.0); P less than 0.05] but an unchanged Km value. The TBS animals had a depressed Vmax as compared with non-tumour-bearing sedentary controls (CS) [141.6 (11.0) vs. 210.1 (15.1); P less than 0.05]. Most of the purine nucleotides in the 'glycolytic' anterior tibial muscle were significantly altered in the TBE animals compared with the TBS animals, but in the mainly 'oxidative' soleus muscle only the level of inosine monophosphate (IMP) was changed. The results indicate that physical exercise can normalise the oxidative capacity and improve the energy state in skeletal muscle in the tumour-bearing host.

Effects of chemotherapy and remission on carbohydrate metabolism in dogs with lymphoma

After a 12-hour fast, blood samples were obtained from 27 dogs with previously untreated lymphoma before and 5, 15, 30, 45, and 60 minutes after an intravenous (IV) challenge with 500 mg/kg dextrose. This procedure was done for each dog before up to five treatments with the IV doxorubicin (30 mg/m2 every 3 weeks). All dogs achieved a complete remission. Samples were assayed for glucose, lactate, and insulin concentrations, and results were compared statistically with those from 16 normal control dogs of similar weight and age undergoing an identical dextrose challenge before and 3 weeks after receiving one dose of IV doxorubicin (30 mg/m2). Glucose, lactate, and insulin concentrations did not change significantly in response to glucose challenge in control dogs after doxorubicin chemotherapy. Lactate and insulin concentrations in untreated dogs with lymphoma were significantly higher than controls. This hyperlactatemia and hyperinsulinemia did not improve when dogs with lymphoma were put into remission with doxorubicin chemotherapy. The results indicate that carbohydrate metabolism is altered in dogs with lymphoma, and that these abnormalities do not improve when a complete remission is obtained with doxorubicin chemotherapy.

Nutrition and cancer. Recent developments

Cancer cachexia is a complex syndrome that results in involuntary weight loss, even in the face of adequate nutritional intake. The profound metabolic abnormalities associated with cancer cachexia affect a large percentage of animals with cancer even before any clinical signs are seen. This paraneoplastic syndrome results in alterations in carbohydrate, lipid, and protein metabolism that, if left untreated, decrease the animal's quality of life and lead to a poor response to cancer therapy. An understanding of the metabolic abnormalities associated with cancer cachexia is of paramount importance to the practicing veterinarian to determine an accurate prognosis and to choose the optimal type of intravenous fluids and nutritional therapy for each patient. Although research identifying the optimal diet for cancer-bearing dogs and cats is still underway, some general principles apply. The first is that the patient should receive nutritional elements orally whenever possible. When oral feeding is not possible, nasogastric, gastrostomy, and jejunostomy tube feeding are viable options. When feeding by the gastrointestinal tract is not possible, parenteral feeding is a practical alternative.

Metabolic effects of cancer

The potential causes of deranged metabolism in cancer are discussed with emphasis on changes in energy metabolism of glucose, fat and protein. The implications of these changes for the treatment of cachexia are then considered.

Alterations in carbohydrate metabolism in canine lymphoma

Following an overnight fast, blood samples were obtained from 14 dogs with previously untreated lymphoma before and 5, 15, 30, 45, 60, and 90 minutes following an intravenous challenge with 500 mg/kg dextrose. Samples were assayed for glucose, lactate, and insulin concentrations and compared statistically with ten control dogs of similar weight and age undergoing an identical dextrose challenge. Dogs with lymphoma had similar glucose tolerance curves when compared with controls. Lactate concentrations were significantly higher (P less than 0.001) at baseline and all time periods of the glucose tolerance test in dogs with lymphoma when compared with controls. Rise in lactate concentrations over baseline levels in the first 30 minutes of the glucose tolerance test were significantly higher in dogs with lymphoma (P = 0.011). Insulin concentrations were significantly higher (P less than 0.001) at baseline and at the 5-, 45-, 60-, and 90-minute time periods of the glucose tolerance test in dogs with lymphoma. Rise in insulin concentrations over baseline in the first 5 minutes of the glucose tolerance test were also significantly greater in dogs with lymphoma (P = 0.021). These results indicate carbohydrate metabolism is altered in dogs with lymphoma. Many of these alterations parallel those observed in human patients suffering from cancer cachexia making canine lymphoma a potential model for further study of the pathogenesis and therapy of cancer cachexia.

Effect of hydrazine sulphate on whole-body protein breakdown measured by 14C-lysine metabolism in lung cancer patients

In a prospective double-blind trial twelve malnourished patients with lung cancer were randomised to receive either placebo or hydrazine sulphate (60 mg three times daily) for 30 days. Fasting lysine flux was determined by a primed 4-hour continuous infusion of 14C-lysine before and after one month of hydrazine treatment. Baseline plasma lysine flux was 2580 (SD 580) mumol/h for the placebo group and 2510 (440) mumol/h for the hydrazine group. After one month the placebo group showed a slight rise to 2920 (450) mumol/h (p = 0.08) and the hydrazine group showed a significant fall to 1840 (750) mumol/h (p less than 0.05); serum albumin fell in the placebo group and was unchanged in the hydrazine group. Administration of hydrazine sulphate to reduce aminoacid flux may favourably influence the metabolic abnormalities in cancer cachexia.

Hydrazine sulfate in cancer patients with weight loss. A placebo-controlled clinical experience

Hydrazine sulfate was evaluated using 24-hour dietary recalls and body weight determinations before and after 30 days of either placebo or hydrazine (60 mg, 3 times/d) oral administration in 101 heavily pretreated cancer patients with weight loss. After 1 month, 83% of hydrazine and only 53% of placebo patients completing repeat evaluation maintained or increased their weight (P less than 0.05). In addition, appetite improvement was more frequent in the hydrazine group (63% versus 25%, P less than 0.05). Although caloric intake was only slightly greater in hydrazine-treated patients, an increased caloric intake was more commonly associated with weight gain in patients receiving hydrazine compared with those receiving placebo (81% versus 53%, respectively). Hydrazine toxicity was mild, with 71% of patients reporting no toxic effects. Hydrazine sulfate circulatory levels were obtained from a subset of 14 patients who completed 30 days of treatment, with a single sample obtained in the morning at least 9 hours after the last dose. Mean maintenance hydrazine sulfate levels, determined using a spectrofluorometric assay, ranged from 0 to 89 ng/ml (mean 45 +/- 16 ng/ml). These data, which demonstrate an association between 1 month of hydrazine sulfate administration and body weight maintenance in patients with cancer, suggest future clinical trials of hydrazine sulfate are indicated to definitively assess its long-term impact on important clinical outcome parameters in defined cancer populations.