Glutamine supplementation in cancer patients receiving chemotherapy: a double-blind randomized study

Glutamine Supplementation as an Anticancer Strategy: A Potential Therapeutic Alternative to the Convention

Glutamine, a multifaceted nonessential/conditionally essential amino acid integral to cellular metabolism and immune function, holds pivotal importance in the landscape of cancer therapy. This review delves into the intricate dynamics surrounding both glutamine antagonism strategies and glutamine supplementation within the context of cancer treatment, emphasizing the critical role of glutamine metabolism in cancer progression and therapy. Glutamine antagonism, aiming to disrupt tumor growth by targeting critical metabolic pathways, is challenged by the adaptive nature of cancer cells and the complex metabolic microenvironment, potentially compromising its therapeutic efficacy. In contrast, glutamine supplementation supports immune function, improves gut integrity, alleviates treatment-related toxicities, and improves patient well-being. Moreover, recent studies highlighted its contributions to epigenetic regulation within cancer cells and its potential to bolster anti-cancer immune functions. However, glutamine implementation necessitates careful consideration of potential interactions with ongoing treatment regimens and the delicate equilibrium between supporting normal cellular function and promoting tumorigenesis. By critically assessing the implications of both glutamine antagonism strategies and glutamine supplementation, this review aims to offer comprehensive insights into potential therapeutic strategies targeting glutamine metabolism for effective cancer management.

Combination L-Glutamine with Gemcitabine and Nab-Paclitaxel in Treatment-Naïve Advanced Pancreatic Cancer: The Phase I GlutaPanc Study Protocol

Advanced pancreatic cancer is underscored by progressive therapeutic resistance and a dismal 5-year survival rate of 3%. Preclinical data demonstrated glutamine supplementation, not deprivation, elicited antitumor effects against pancreatic ductal adenocarcinoma (PDAC) alone and in combination with gemcitabine in a dose-dependent manner. The GlutaPanc phase I trial is a single-arm, open-label clinical trial investigating the safety of combination L-glutamine, gemcitabine, and nab-paclitaxel in subjects (n = 16) with untreated, locally advanced unresectable or metastatic pancreatic cancer. Following a 7-day lead-in phase with L-glutamine, the dose-finding phase via Bayesian design begins with treatment cycles lasting 28 days until disease progression, intolerance, or withdrawal. The primary objective is to establish the recommended phase II dose (RP2D) of combination L-glutamine, gemcitabine, and nab-paclitaxel. Secondary objectives include safety of the combination across all dose levels and preliminary evidence of antitumor activity. Exploratory objectives include evaluating changes in plasma metabolites across multiple time points and changes in the stool microbiome pre and post L-glutamine supplementation. If this phase I clinical trial demonstrates the feasibility of L-glutamine in combination with nab-paclitaxel and gemcitabine, we would advance the development of this combination as a first-line systemic option in subjects with metastatic pancreatic cancer, a high-risk subgroup desperately in need of additional therapies.

Combination Compositions Composed of l-Glutamine and Si-Jun-Zi-Tang Might Be a Preferable Choice for 5-Fluorouracil-Induced Intestinal Mucositis: An Exploration in a Mouse Model

Intestinal mucositis is a common toxicity of many anti-neoplastic therapies that negatively influences health, the quality of life, economic outcomes, and even the success of cancer treatment. Unfortunately, there is presently no optimal medicine that is able to effectively manage this condition. l-glutamine is one of the most frequently used agent in practice among the limited treatment choices due to its safety and inexpensiveness despite there being a lack of evidence. Previous studies indicated that l-glutamine may alleviate mucositis and mucosal atrophy but failed to improve patients' macroscopic conditions, such as the occurrence of diarrhea. A compound glutamine capsule (G-SJZ), composed of l-glutamine and the traditional Chinese herbal formula Si-Jun-Zi-Tang, has been used in China for 23 years to treat many types of gastrointestinal diseases, including gastrointestinal reactions induced by radiotherapy and chemotherapy. However, the exact effect of G-SJZ on intestinal mucositis is unclear, and moreover, whether l-glutamine combined with Si-Jun-Zi-Tang is more effective than l-glutamine alone have not been studied. In the current study, we explored the effects of G-SJZ and l-glutamine in a mouse model of intestinal mucositis induced by 5-fluorouracil (5-Fu). The results revealed that pretreatment with G-SJZ ameliorated the physical manifestations of weight loss and the severity of diarrhea following continuous 5-Fu injections in mice. Likewise, the histopathological damage and the destruction of villus and crypt structures in the intestinal mucosa as well as the increase in circulating intestinal injury markers caused by 5-Fu were reversed with G-SJZ pretreatment. Furthermore, the protective effect of G-SJZ was accompanied by modulations in the immunohistochemical expression of tight junction proteins. Interestingly, although treatment with a dose of l-glutamine alone that was equivalent to the dose in G-SJZ also showed a protective effect, it did not appear to be as strong as treatment with G-SJZ. Si-Jun-Zi-Tang in G-SJZ may compensate for the deficiencies of l-glutamine in this model which seems not to be related to the regulation of tight junction proteins. Our study is the first to suggest that the combined use of l-glutamine and Si-Jun-Zi-Tang might be more effective than l-glutamine alone despite exact mechanism still needs further study. Because of the limited number of therapeutic agents, G-SJZ is likely to be a preferable choice for intestinal mucositis.

Effects of Immunonutrition on Chemoradiotherapy Patients: A Systematic Review and Meta-Analysis

OBJECTIVE

We conducted a systematic review to assess the effects of immunonutrition on chemoradiotherapy patients.

METHODS

We searched the Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, CINAHL, and the Web of Science. We assessed the risk of bias using the Cochrane Risk of Bias tool. Our primary outcomes were the incidence of oral mucositis and diarrhea. The secondary outcomes were the incidence of esophagitis, grade ≥3 oral mucositis, grade ≥3 diarrhea, grade ≥3 esophagitis, and body weight loss.

RESULTS

A total of 1478 patients and 27 studies were included. There were no significant differences in the incidence of oral mucositis (relative risk [RR] = 0.91; 95% confidence interval [CI], 0.79-1.05), diarrhea (RR = 0.89; 95% CI, 0.76-1.05), or esophagitis (RR = 0.55; 95% CI, 0.11-2.86) between the immunonutrition group and standard nutrition/placebo group. Nevertheless, immunonutrition significantly reduced the incidence of grade ≥3 oral mucositis (RR = 0.45; 95% CI, 0.22-0.92), grade ≥3 diarrhea (RR = 0.56; 95% CI, 0.35-0.88), grade ≥3 esophagitis (RR = 0.15; 95% CI, 0.04-0.54), and losing >5% body weight (RR = 0.34; 95% CI, 0.18-0.64).

CONCLUSIONS

In this study, immunonutrition failed to reduce the incidence rates of oral mucositis, diarrhea, or esophagitis but was conducive to significantly improving the severity of oral mucositis and diarrhea esophagitis and reducing the rate of body weight loss.

Theanine, an antitumor promoter, induces apoptosis of tumor cells via the mitochondrial pathway

Theanine, an active component of green tea (Camellia sinensis), is considered a modulator of chemotherapy. To further investigate the anticancer activity of theanine, the present study investigated the cytotoxic effect of theanine at the concentration of 600 µg/ml, in the human HepG2 hepatoblastoma and HeLa adenocarcinoma cell lines, in comparison with the normal L02, H9c2 and HEK293 cell lines using a MTT assay. It was found that theanine induced cell death in the tumor cells, but not in the normal cells. Notably, when glutamine was restricted or reduced in the cell culture medium, the cell death induced by theanine was significantly enhanced. A terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling assay indicated that DNA damage was induced in theanine‑treated HepG2 cells. Further experiments demonstrated that theanine caused HepG2 cell apoptosis through the mitochondrial pathway, with a loss of membrane potential and the release of apoptosis‑inducing factor, endonuclease G and cytochrome c. Western blot analysis and caspase activity detection also revealed that caspase‑9 and caspase‑3 were activated, whereas caspase‑8 remained inactive. These observations suggested that theanine exerted potent cytotoxicity on tumor cells when glutamine was restricted.

Oral Glutamine Ameliorates Chemotherapy-induced Changes of Intestinal Permeability and Does not Interfere with the Antitumor Effect of Chemotherapy in Patients with Breast Cancer: A Prospective Randomized Trial

Aims and Background

Sixty patients with breast cancer were randomly assigned to oral glutamine or placebo pre-neoadju-vant chemotherapy (CEF regimen).

Methods and Study Design

Oral glutamine supplementation was continued for at least 12 days. Patients kept a daily record of diarrhea and stomatitis. The plasma glutamine level, intestinal permeability (lactulose-mannitol test), and tumor size were analyzed. The expression of Ki-67 and PCNA antigens in breast carcinoma was assessed.

Results

The plasma glutamine level was significantly higher in the glutamine group than in the placebo group (420.39 ± 52.39 mmol/L vs 309.76 ± 42.34 mmoi/L, P <0.05). After one cycle of chemotherapy, the lactulose-mannitol ratio was higher in the placebo group than in the glutamine group (0.0630 ± 0.0091 vs 0.0471 ± 0.0094, P <0.05). No differences were observed in the grades of stomatitis and diarrhea, in the changes in tumor size, and in the expression of Ki-67 and PCNA antigens between the two groups.

Conclusions

Prophylactic oral glutamine could ameliorate the neoadjuvant chemotherapy-induced increase in intestinal permeability, but had no significant positive clinical effect on stomatitis and diarrhea and did not interfere with the antitumor effect of chemotherapy.

Clinical practice guidelines on the evidence-based use of integrative therapies during and after breast cancer treatment

Answer questions and earn CME/CNE Patients with breast cancer commonly use complementary and integrative therapies as supportive care during cancer treatment and to manage treatment-related side effects. However, evidence supporting the use of such therapies in the oncology setting is limited. This report provides updated clinical practice guidelines from the Society for Integrative Oncology on the use of integrative therapies for specific clinical indications during and after breast cancer treatment, including anxiety/stress, depression/mood disorders, fatigue, quality of life/physical functioning, chemotherapy-induced nausea and vomiting, lymphedema, chemotherapy-induced peripheral neuropathy, pain, and sleep disturbance. Clinical practice guidelines are based on a systematic literature review from 1990 through 2015. Music therapy, meditation, stress management, and yoga are recommended for anxiety/stress reduction. Meditation, relaxation, yoga, massage, and music therapy are recommended for depression/mood disorders. Meditation and yoga are recommended to improve quality of life. Acupressure and acupuncture are recommended for reducing chemotherapy-induced nausea and vomiting. Acetyl-L-carnitine is not recommended to prevent chemotherapy-induced peripheral neuropathy due to a possibility of harm. No strong evidence supports the use of ingested dietary supplements to manage breast cancer treatment-related side effects. In summary, there is a growing body of evidence supporting the use of integrative therapies, especially mind-body therapies, as effective supportive care strategies during breast cancer treatment. Many integrative practices, however, remain understudied, with insufficient evidence to be definitively recommended or avoided. CA Cancer J Clin 2017;67:194-232. © 2017 American Cancer Society.

A phase III study evaluating oral glutamine and transforming growth factor-beta 2 on chemotherapy-induced toxicity in patients with digestive neoplasm

BACKGROUND

Patients with gastrointestinal (GI) cancer are exposed to cachexia, which is highly correlated with chemotherapy-induced side effects. Research suggests that specific immunonutrients could prevent such toxicities.

AIMS

The primary objective of this phase III study was to evaluate the efficacy of glutamine and transforming growth factor-β2 (TGF-β2) in the prevention of grade 3-4 non-hematological toxicities induced by chemotherapy in patients with GI cancer.

PATIENTS AND METHODS

We designed a double-blind, randomized, controlled and multicenter trial stratified according to center, type of chemotherapy, presence of cachexia, and age. Patients were randomized to receive either Clinutren Protect(®) (CP) or a control isocaloric diet (without TGF-β2 or glutamine).

RESULTS

Between November 2007 and October 2011, 210 patients were enrolled in the study, of which 201 were included in the intention-to-treat analysis. Grade 3-4 non-hematological toxicities were not significantly different between the CP and control groups when evaluated by univariate and multivariate analyses. Likewise, no difference was observed regarding grade 3-4 hematological toxicities or reasons for treatment interruption.

CONCLUSION

This randomized study does not support the hypothesis that oral glutamine and TGF-β2 supplementation is effective to reduce grade 3 or 4 non-hematological toxicities induced by chemotherapy in patients with GI neoplasm.

Clinical practice guidelines on the use of integrative therapies as supportive care in patients treated for breast cancer

BACKGROUND

The majority of breast cancer patients use complementary and/or integrative therapies during and beyond cancer treatment to manage symptoms, prevent toxicities, and improve quality of life. Practice guidelines are needed to inform clinicians and patients about safe and effective therapies.

METHODS

Following the Institute of Medicine's guideline development process, a systematic review identified randomized controlled trials testing the use of integrative therapies for supportive care in patients receiving breast cancer treatment. Trials were included if the majority of participants had breast cancer and/or breast cancer patient results were reported separately, and outcomes were clinically relevant. Recommendations were organized by outcome and graded based upon a modified version of the US Preventive Services Task Force grading system.

RESULTS

The search (January 1, 1990-December 31, 2013) identified 4900 articles, of which 203 were eligible for analysis. Meditation, yoga, and relaxation with imagery are recommended for routine use for common conditions, including anxiety and mood disorders (Grade A). Stress management, yoga, massage, music therapy, energy conservation, and meditation are recommended for stress reduction, anxiety, depression, fatigue, and quality of life (Grade B). Many interventions (n = 32) had weaker evidence of benefit (Grade C). Some interventions (n = 7) were deemed unlikely to provide any benefit (Grade D). Notably, only one intervention, acetyl-l-carnitine for the prevention of taxane-induced neuropathy, was identified as likely harmful (Grade H) as it was found to increase neuropathy. The majority of intervention/modality combinations (n = 138) did not have sufficient evidence to form specific recommendations (Grade I).

CONCLUSIONS

Specific integrative therapies can be recommended as evidence-based supportive care options during breast cancer treatment. Most integrative therapies require further investigation via well-designed controlled trials with meaningful outcomes.

Systematic review of agents for the management of gastrointestinal mucositis in cancer patients

PURPOSE

The aim of this study was to review the available literature and define clinical practice guidelines for the use of agents for the prevention and treatment of gastrointestinal mucositis.

METHODS

A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). The body of evidence for each intervention, in each cancer treatment setting, was assigned an evidence level. Based on the evidence level, one of the following three guideline determinations was possible: recommendation, suggestion, and no guideline possible.

RESULTS

A total of 251 clinical studies across 29 interventions were examined. Panel members were able to make one new evidence-based negative recommendation; two new evidence-based suggestions, and one evidence-based change from previous guidelines. Firstly, the panel recommends against the use of misoprostol suppositories for the prevention of acute radiation-induced proctitis. Secondly, the panel suggests probiotic treatment containing Lactobacillus spp., may be beneficial for prevention of chemotherapy and radiotherapy-induced diarrhea in patients with malignancies of the pelvic region. Thirdly, the panel suggests the use of hyperbaric oxygen as an effective means in treating radiation-induced proctitis. Finally, new evidence has emerged which is in conflict with our previous guideline surrounding the use of systemic glutamine, meaning that the panel is unable to form a guideline. No guideline was possible for any other agent, due to inadequate and/or conflicting evidence.

CONCLUSIONS

This updated review of the literature has allowed new recommendations and suggestions for clinical practice to be reached. This highlights the importance of regular updates.

Clinical trials in integrative therapies

OBJECTIVES

To review clinical trials in natural products and mind-body therapies for oncology symptom management, to discuss issues related to developing clinical trials in this area, and outline examples of rigorous and innovative study design.

DATA SOURCES

Peer reviewed literature.

CONCLUSION

Most of the evidence for the integrative therapies reviewed is derived from phase II trials, and is considered preliminary. More research is needed in these therapies to clearly articulate their role in the management of oncology symptoms. Innovative strategies and methodologies for studying integrative therapies have been demonstrated.

IMPLICATIONS FOR NURSING PRACTICE

It is necessary to critically evaluate the literature to be able to educate patients about integrative therapies. Investigators should expand on well-designed studies that demonstrate clinically important effects. Dissemination trials may be a good strategy, once data exists, to move integrative therapies into the care of patients.

Oral glutamine supplementation during preoperative radiochemotherapy in patients with rectal cancer: a randomised double blinded, placebo controlled pilot study

BACKGROUND & AIMS

Enteral glutamine may have protective effects on gut function and reduce metabolic stress in patients receiving radiochemotherapy. The aim of our study was to evaluate its influence in patients with rectal cancer undergoing preoperative radiochemotherapy.

METHODS

We performed a randomized double blind, placebo controlled pilot study in 33 patients. 30 g of glutamine, average dose 0.41 g/kg (SD = 0.07) g/kg/day was administered orally in three doses per day for five weeks during preoperative radiochemotherapy of rectal cancer. 30 g of maltodextrin was given as placebo. Body weight was measured and NRS 2002 screening was performed before and after treatment. Bowel function was evaluated by stool consistency and frequency. Plasma levels of inflammatory parameters and hormones were measured.

RESULTS

There was no difference between groups in frequency and severity of diarrhoea during radiochemotherapy (p = 0.5 and p = 0.39 respectively), insulin levels significantly increased in both groups, IL-6 only in glutamine group.

CONCLUSION

Results of this small pilot study in rectal cancer patients receiving preoperative radiochemotherapy, showed that ingestion of larger quantities of glutamine given more often as previously reported did not diminish the incidence and severity of diarrhoea and did not affect inflammatory and metabolic activity compared to the placebo treatment with maltodextrin.

The significance of altered gastrointestinal permeability in cancer patients. Curr Opin Support Palliat Care. 2011;5:47-54. [PMID: 21326003 DOI: 10.1097/SPC.0b013e328343a043]

PURPOSE OF REVIEW

The diagnosis and assessment of severity of intestinal mucosal damage in cancer patients treated by anticancer therapy still rely mostly on anamnestic data. We review here studies reporting on the use of intestinal permeability measurements in cancer patients before and during treatment.

RECENT FINDINGS

The concept of intestinal permeability is based on differential permeability of intestinal mucosa to molecular markers, including monosaccharides and disaccharides, along the crypt-villus axis. Cytotoxic drugs and/or radiation impair replacement of intestinal epithelia and induce flattening of the villi, leading to increased exposure of luminal contents to crypts and increased disaccharide absorption. Increased disaccharide/monosaccharide ratio and decreased xylose absorption have been described in patients treated by radiotherapy as well as different cytotoxic or targeted agents across a spectrum of malignant disorders. Intestinal permeability changes correlated with clinical manifestations, including diarrhea, mucositis, neutropenic enterocolitis and systemic infections. The measurement of intestinal permeability has also been used as a surrogate end-point in interventional studies.

SUMMARY

Intestinal permeability testing using nonmetabolized sugars may represent a tool for noninvasive objective assessment of intestinal toxicity of anticancer therapy.

Total parenteral nutrition in children and adolescents treated with high-dose chemotherapy followed by autologous haematopoietic transplants

Total parenteral nutrition (TPN) is still of great importance for haematopoietic stem cell transplantation (HSCT) patients because one of the major adverse effects of the high-dose therapy followed by HSCT is an inadequate oral nutrition intake. The aim of the study was analysis of TPN of young patients in the HSCT period. Twenty-two patients 1·8–20·8 year-old, median 5·4, treated with high-dose therapy and autologous HSCT because of malignancy were included into the study. Grafts contained 1·35–7·9 × 106, median 3·75 × 106CD34+ cells/kg. Engraftment occurred as follows: granulocytes >0·5 × 109/l on +11 d (8–25); platelets >20 × 109/l on +23 d (12–67). Patients were given isoenergetic, isonitrogenous TPN until they consumed less than 50 % of their required diet orally. Proteins intake was 0·8–2·0 g/kg per d, fats intake 1·0–3·0 g/kg per d. Total non-proteins energies–nitrogen grams index was 140:1–200:1. Supplementation of electrolytes, microelements, trace elements and vitamins was dependent on individual patient requirement. TPN duration did not correlate with CD34+cells number but correlated with platelets reconstitution. The assessment of nutritional condition demonstrated no differences in anthropometric parameters, but increase of serum albumin levels after TPN. Requirement for P3 − was above the normal ranges and correlated positively with platelets reconstitution. Requirement for P3 − and K+was higher in patients with mucositis than in other patients. Any complications due to TPN were observed. Adequately composed isoenergetic and isonitrogenous TPN with replacement of electrolytes according to their requirement in the early post-transplantation period allows not only improvement in nutritional status of patients but also could contribute to reconstitution of haematopoiesis.

Clinical trial: prophylactic intravenous alanyl-glutamine reduces the severity of gastrointestinal toxicity induced by chemotherapy--a randomized crossover study

BACKGROUND

Glutamine has been shown in numerous studies to reduce intestinal permeability which can be increased by chemotherapy. However, there have been few reports that conduct on its clinical effect on gastrointestinal toxicity.

AIM

To examine whether prophylactic intravenous alanyl-glutamine dipeptide can ameliorate clinical manifestations of gastrointestinal toxicity induced by chemotherapy.

METHODS

Forty-four patients with gastric or colorectal cancer developing WHO side-effect grading system of grade 2 or higher were randomized to either control group (n = 22) or Gln group (n = 22) during next cycle of chemotherapy. Patients were crossed over to the alternate treatment during chemotherapy cycle 2. In the control group, the patients received the same chemotherapy regimens as screening cycle and in the Gln group, the patients received chemotherapy and alanyl-glutamine. Prophylactic intravenous 20 g of alanyl-glutamine dipeptide was given for 5 days.

RESULTS

Compared with the control group, the plasma glutamine level in the Gln group was significantly higher and the plasma endotoxin level was significantly lower. The scores of nausea/vomiting and diarrhoea decreased significantly.

CONCLUSION

Prophylactic intravenous alanyl-glutamine is effective in preventing intestinal permeability disruption induced by chemotherapy and clinical manifestations of gastrointestinal toxicity.

Pilot Study: effects of parenteral glutamine dipeptide supplementation on neutrophil functions and prevention of chemotherapy-induced side-effects in acute myeloid leukaemia patients

The effect of parenteral glutamine dipeptide (Gln) supplementation on neutrophil phagocytosis, superoxide anion generation (SAG), prevention of chemotherapy-induced side-effects and cost-effectiveness was examined in a pilot study of acute myeloid leukaemia (AML) patients receiving chemotherapy. Sixteen AML patients were randomized to receive intravenous supplementation with Gln (30 g/day) or an equivalent quantity (25 g/day) of a standard amino acid mixture (control) on days 1 - 5 of chemotherapy. Complete blood count was evaluated twice a week until hospital discharge, and neutrophil phagocytosis and SAG were measured when absolute neutrophil count reached > 500 /microl. Patients were observed for development of infection, mucositis and diarrhoea. In Gln-treated patients, the percentage of neutrophil phagocytosis and the SAG levels were significantly higher than in control patients (20.5 +/- 6.0% and 18.9 +/- 2.9 nmol/10(6) neutrophils per 10 min, respectively). The Gln-treated patients lost significantly less weight, tended to have shorter in-patient duration and had less severe oral mucositis than controls. This pilot study provides preliminary indication that parenteral Gln supplementation enhances neutrophil phagocytic function, maintains nutritional status and is cost effective. Parenteral Gln may also prevent oral mucositis, although further studies involving more patients need to be undertaken to confirm this and the other results.

Dietary supplement use in cancer care: help or harm

Conventional wisdom generally recommends complete avoidance of all dietary supplements, especially during chemotherapy and radiation. This interdiction persists, in spite of high rates of dietary supplement use by patients throughout all phases of cancer care, and can result in patients' perceptions of physicians as negative, thus leading to widespread nondisclosure of use. A review of the clinical literature shows that some evidence for harm does exist; however, data also exist that show benefit from using certain well-qualified supplements. Physicians should increase their knowledge base about dietary supplement use in cancer and consider all of the data when advising patients. Strategies that are patient-centered and reflect the complete array of available evidence lead to more nuanced messages about dietary supplement use in cancer. This should encourage greater disclosure of use by patients and ultimately increase safety and efficacy for patients choosing to use dietary supplements during cancer care.

Prevention of radiochemotherapy-induced esophagitis with glutamine: results of a pilot study

PURPOSE

To assess the usefulness of oral glutamine to prevent radiochemotherapy-induced esophagitis in patients with lung cancer, and to determine the dosimetric parameter predictive of esophagitis.

METHODS AND MATERIALS

Seventy-five patients were enrolled; 34.7% received sequential radiochemotherapy, and 65.3% received concomitant radiochemotherapy. Every patient received prophylactic glutamine powder in doses of 10 g/8 h. Prescribed radiation doses were 45-50 Gy to planning target volume (PTV)1 (gross tumor volume plus wide margins) and 65-70 Gy to PTV2 (reduced margins). The primary endpoint was the incidence of Grade 2 or greater acute esophagitis.

RESULTS

No patient experienced glutamine intolerance or glutamine-related toxicity. Seventy-three percent of patients who received sequential chemotherapy and 49% of those who received concomitant chemotherapy did not present any form of esophagitis. V50 was the dosimetric parameter with better correlation between esophagitis and its duration. A V50 of <or=30% had a 22% risk of esophagitis Grade >or=2, which increased to 71% with a V50 of >30% (p = 0.0009).

CONCLUSIONS

The use of oral glutamine may have an important role in the prevention of esophageal complications of concomitant radiochemotherapy in lung cancer patients. However, randomized trials are needed to corroborate that effect. V50 is the dosimetric parameter with better correlation with esophagitis grade and duration.

Glutamine: do the data support the cause for glutamine supplementation in humans?

This review examines the preclinical rationale for using glutamine supplements and reviews the prospective randomized trials using glutamine to improve outcomes in patients. A special role for glutamine in gut physiology and in management of a variety of serious illnesses has been suggested, because it is the most abundant extracellular amino acid, and is used at high rates by the gut, liver, central nervous system, and immune cells. A state of relative Gln deficiency has been postulated in humans based on the decrease in plasma Gln in acute critical illness, but the decrease in plasma Gln is not specific for that amino acid, predicts only poorer outcome, and has not been validated to identify a deficiency state. Current evidence does not necessarily predict a special need or role for Gln in critical illness. Clinical efficacy of supplemental Gln has been difficult to demonstrate, possibly related to the lack of a Gln deficiency state, the wide range of end points used that reflect the lack of certainty of the predicted effect of supplementation, the heterogeneous patient populations studied, the lack of stable clinical course during the study, the lack of adequate power, and the relatively short follow-up period. Prospective randomized clinical trials of Gln supplementation were reviewed in patients with short-bowel syndrome, during cancer chemotherapy and in bone marrow transplantation, and in surgical, burn, and intensive care unit patients. No firm recommendation can be made at this time. Future studies should seek to develop a more standard and stable design for intervention in sufficiently powered studies.

A Phase II Trial of Irinotecan, 5-Fluorouracil and Leucovorin Combined with Celecoxib and Glutamine as First-Line Therapy for Advanced Colorectal Cancer

OBJECTIVES

Preclinical and clinical data indicate that cyclooxygenase-2 (COX-2) is a bona fide molecular target for colorectal cancer (CRC). Glutamine may decrease chemotherapy-associated diarrhea. This study was designed to address whether the addition of celecoxib, a COX-2 inhibitor, and glutamine would improve the efficacy and decrease the toxicities of the irinotecan, fluorouracil and leucovorin (IFL) regimen.

METHODS

All patients received the original IFL regimen plus celecoxib (400 mg, po, every 12 h continuously while on trial) and glutamine (10 g, po, every 8 h continuously while on chemotherapy).

RESULTS

Of the 41 patients enrolled, 40 patients received between 1 and 6 cycles of treatment. This regimen was associated with significant toxicities: 45.0% had grade 3 diarrhea, 35.0% grade 3/4 neutropenia, 22.5% hospitalization, 10.0% deep vein thrombosis and 2 treatment-related deaths. The overall response rate was 47.2%. The median progression-free survival was 6.7 months. The median overall survival was 16.3 months. The 12-month overall survival rate was 54.8%. COX-2 expression was present in 63.2% of the specimens evaluated. There was no significant correlation between COX-2 expression and response to chemotherapy (p = 0.739).

CONCLUSION

The addition of celecoxib and glutamine appears not to improve the efficacy or decrease the toxicities of IFL for the treatment of metastatic CRC.

Vincristine-induced urinary bladder paralysis

The authors describe the development of bladder paralysis in a child with acute lymphoblastic leukemia undergoing maintenance chemotherapy. Immediately before the adverse clinical event, the child had received vincristine intravenously and triple therapy with hydrocortisone, cytosine arabinoside, and methotrexate intrathecally and had begun a 5-day pulse of prednisolone. The authors conclude that the ensuing reversible bladder paralysis was related to the vincristine. The clinical event resolved, and vincristine was deleted from the child's subsequent therapy until full recovery was achieved. The authors advise recognition of this problem and discontinuation of the vincristine if transient bladder paralysis develops until symptoms completely disappear.

Herbs or natural products that decrease cancer growth part one of a four-part series

PURPOSE/OBJECTIVES

To provide evidence-based research information about 31 herbs and natural products that have shown potential in early research to decrease cancer growth or as adjuncts with cancer treatment.

DATA SOURCES

Names of herbs and natural products with potential to decrease cancer growth have been selected from listings in the Natural Medicines Comprehensive Database and Lawrence Review of Natural Products-Monograph System. Information about these herbs has been found in evidence-based studies cited in references.

DATA SYNTHESIS

In preliminary studies, 31 herbs and natural products appear to have potential for cancer treatment.

CONCLUSIONS

This preliminary evidence may be useful to healthcare professionals and patients with cancer.

IMPLICATIONS FOR NURSING

The information in this article is designed to provide quick access for healthcare professionals working in clinical oncology. Oncology nurses who have this information can become resources for patients and other healthcare professionals.

Prevention of chemotherapy and radiation toxicity with glutamine

GOALS OF THE WORK

Malignancy produces a state of physiologic stress that is characterized by a relative deficiency of glutamine, a condition that is further exacerbated by the effects of cancer treatment. Glutamine deficiency may impact on normal tissue tolerance to antitumor treatment, and may lead to dose reductions and compromised treatment outcome. Providing supplemental glutamine during cancer treatment has the potential to abrogate treatment-related toxicity. We reviewed the available data on the use of glutamine to decrease the incidence and severity of adverse effects due to chemotherapy and/or radiation in cancer patients.

METHODS

We performed a search of the MEDLINE database during the time period 1980-2003, and reviewed the English language literature of both human and animal studies pertaining to the use of glutamine in subjects with cancer. We also manually searched the bibliographies of published articles for relevant references.

MAIN RESULTS

The available evidence suggests that glutamine supplementation may decrease the incidence and/or severity of chemotherapy-associated mucositis, irinotecan-associated diarrhea, paclitaxel-induced neuropathy, hepatic veno-occlusive disease in the setting of high dose chemotherapy and stem cell transplantation, and the cardiotoxicity that accompanies anthracycline use. Oral glutamine supplementation may enhance the therapeutic index by protecting normal tissues from, and sensitizing tumor cells to chemotherapy and radiation-related injury.

CONCLUSIONS

The role of glutamine in the prevention of chemotherapy and radiation-induced toxicity is evolving. Glutamine supplementation is inexpensive and it may reduce the incidence of gastrointestinal, neurologic, and possibly cardiac complications of cancer therapy. Further studies, particularly placebo-controlled phase III trials, are needed to define its role in chemotherapy-induced toxicity.

Nutritional benefits of enteral alanyl-glutamine supplementation on rat small intestinal damage induced by cyclophosphamide

BACKGROUND

Glutamine is the principal fuel used by the small intestine. Although the parental administration of glutamine promotes intestinal mucosal growth, it is controversial whether enteral glutamine is effective against small intestinal damage caused by chemotherapy. To further evaluate the benefits of enteral supplementation, peptide and amino acid transporter functions must be considered.

METHOD

Rats were given cyclophosphamide (CPM) intraperitoneally (300 mg/kg). Expression of the amino acid transporter, B0 and peptide transporter (PepT1) in the jejunal mucosa was initially examined by northern blot analysis. Rats received a bolus oral supplement of an alanine (1.22 g/kg/day) plus glutamine (2.0 g/kg/day) mixture, alanyl-glutamine (2.972 g/kg/day) or saline as a control, for 7 days after CPM administration.

RESULTS

Levels of B0 mRNA remained unchanged at both 3 and 7 days after CPM administration. Conversely, PepT1 mRNA increased significantly after CPM administration, and reached 200% of the initial level 7 days later. In rats given alanyl-glutamine, the mucosal wet weight and protein content increased significantly with increasing villus height at 3 and 7 days, compared with the alanine plus glutamine mixture. The plasma glutamine concentration in the alanyl-glutamine group, but not the alanine plus glutamine mixture group, increased significantly compared with that in the saline group.

CONCLUSION

Enteral supplementation with an alanyl-glutamine but not alanine plus glutamine mixture prevents intestinal damage, as demonstrated by increased peptide transport expression and an elevated plasma glutamine concentration after CPM administration.

Phase III double-blind study of glutamine versus placebo for the prevention of acute diarrhea in patients receiving pelvic radiation therapy

PURPOSE

A phase III, randomized, double-blind study was conducted by the North Central Cancer Treatment Group to determine the efficacy and toxicity of oral glutamine for the prevention of acute diarrhea in patients receiving pelvic radiation therapy (RT).

PATIENTS AND METHODS

All 129 patients enrolled from 14 institutions between February 1998 and October 1999 were eligible. Patients received 4 g of glutamine or placebo orally, twice a day, beginning with the first or second day of RT and continuing for 2 weeks after RT. During treatment, patients were assessed weekly for toxicity, and a bowel function questionnaire was administered. The primary measures of treatment efficacy were diarrhea levels measured by maximum grade of diarrhea, incidence of diarrhea, and average diarrhea score. After completion of RT, the bowel function questionnaire was administered weekly for 4 weeks and at 12 and 24 months. Toxicity was measured by National Cancer Institute common toxicity criteria.

RESULTS

The median age of patients was 69 years (range, 34 to 86 years). The two treatment arms were balanced with respect to all baseline factors. There were no significant differences in toxicity by treatment. Quality-of-life scores and the mean number of problems reported on the bowel function questionnaire were virtually identical for both treatment groups. The incidence of grade 3 or higher diarrhea was 20% for the glutamine arm and 19% for the placebo arm (P =.99). The maximum number of stools per day was 5.1 for the glutamine arm and 5.2 for the placebo arm (P =.99).

CONCLUSION

There is no evidence of a beneficial effect of glutamine during pelvic RT.

II. Glutamine and glutamate

Glutamine and glutamate with proline, histidine, arginine and ornithine, comprise 25% of the dietary amino acid intake and constitute the "glutamate family" of amino acids, which are disposed of through conversion to glutamate. Although glutamine has been classified as a nonessential amino acid, in major trauma, major surgery, sepsis, bone marrow transplantation, intense chemotherapy and radiotherapy, when its consumption exceeds its synthesis, it becomes a conditionally essential amino acid. In mammals the physiological levels of glutamine is 650 micromol/l and it is one of the most important substrate for ammoniagenesis in the gut and in the kidney due to its important role in the regulation of acid-base homeostasis. In cells, glutamine is a key link between carbon metabolism of carbohydrates and proteins and plays an important role in the growth of fibroblasts, lymphocytes and enterocytes. It improves nitrogen balance and preserves the concentration of glutamine in skeletal muscle. Deamidation of glutamine via glutaminase produces glutamate a precursor of gamma-amino butyric acid, a neurotransmission inhibitor. L-Glutamic acid is a ubiquitous amino acid present in many foods either in free form or in peptides and proteins. Animal protein may contain from 11 to 22% and plants protein as much as 40% glutamate by weight. The sodium salt of glutamic acid is added to several foods to enhance flavor. L-Glutamate is the most abundant free amino acid in brain and it is the major excitatory neurotransmitter of the vertebrate central nervous system. Most free L-glutamic acid in brain is derived from local synthesis from L-glutamine and Kreb's cycle intermediates. It clearly plays an important role in neuronal differentiation, migration and survival in the developing brain via facilitated Ca++ transport. Glutamate also plays a critical role in synaptic maintenance and plasticity. It contributes to learning and memory through use-dependent changes in synaptic efficacy and plays a role in the formation and function of the cytoskeleton. Glutamine via glutamate is converted to alpha-ketoglutarate, an integral component of the citric acid cycle. It is a component of the antioxidant glutathione and of the polyglutamated folic acid. The cyclization of glutamate produces proline, an amino acid important for synthesis of collagen and connective tissue. Our aim here is to review on some amino acids with high functional priority such as glutamine and to define their effective activity in human health and pathologies.

Protective nutrients and functional foods for the gastrointestinal tract

Epithelial and other cells of the gastrointestinal mucosa rely on both luminal and bloodstream sources for their nutrition. The term functional food is used to describe nutrients that have an effect on physiologic processes that is separate from their established nutritional function, and some of these nutrients are proposed to promote gastrointestinal mucosal integrity. We review the recent in vitro, animal, and clinical experiments that evaluated the role of several types of gastrointestinal functional foods, including the amino acids glutamine and arginine, the essential micronutrients vitamin A and zinc, and 2 classes of food additives, prebiotics and probiotics. Many of the data from preclinical studies support a strong role for enteral nutrients in gastrointestinal health; in comparison, the data from human studies are limited. In some cases, impressive data from in vitro and animal studies have not been replicated in human trials. Other clinical trials have shown positive health benefits, but some of those studies were plagued by flaws in study design or analysis. The methods available to detect important changes in human gastrointestinal function and structure are still limited, but with the development of more sensitive measures of gastrointestinal function, the effects of specific nutrients may be more easily detected. This may facilitate the development of phase 3 clinical trials designed to more rigorously evaluate the effects of a particular nutrient by focusing on valid and reliable outcome measures. Regulatory changes in the way in which health claims can be made for dietary supplements should also be encouraged.

Glutamine: indicated in cancer care?

Glutamine is a nonessential amino acid contained in most dietary proteins and provides immune functions and fuel for the small intestine. For healthy people, dietary glutamine (from protein) usually is considered adequate. Results of research evaluating the potential benefits of glutamine during cancer therapy are encouraging but remain inconclusive. Some researchers have suggested recently that glutamine may, in fact, be a conditionally essential amino acid (Buchman, 2001). Decreases in glutamine levels after trauma or major burns, postoperatively, and in patients with diseases such as inflammatory bowel disease, AIDS, and cancer are widely recognized and acknowledged (Medina, 2001; Miller, 1999). The interpretation of data suggesting that glutamine supplementation is of benefit in almost any clinical situation is controversial. Additional research is needed to confirm the mechanism of action and efficacy of glutamine as adjuvant therapy in patients receiving cancer treatment.

Glutamine supplementation in bone marrow transplantation

An increasing number of clinical investigations have focused on supplementation of specialized enteral and parenteral nutrition with the amino acid glutamine. This interest derives from strong evidence in animal models and emerging clinical data on the efficacy of glutamine administration following chemotherapy, trauma, sepsis and other catabolic conditions. Glutamine has protein-anabolic effects in stressed patients and, among many key metabolic functions, is used as a major fuel/substrate by cells of the gastrointestinal epithelium and the immune system. These effects may be particularly advantageous in patients undergoing bone marrow transplantation (BMT), who exhibit post-transplant body protein wasting, gut mucosal injury and immunodeficiency. Studies to date indicate that enteral and parenteral glutamine supplementation is well tolerated and potentially efficacious after high-dose chemotherapy or BMT for cancer treatment. Although not all studies demonstrate benefits, sufficient positive data have been published to suggest that this nutrient should be considered as adjunctive metabolic support of some individuals undergoing marrow transplant. However, BMT is a rapidly evolving clinical procedure with regard to the conditioning and supportive protocols utilized. Thus, additional randomized, double-blind, controlled clinical trials are indicated to define the efficacy of glutamine with current BMT regimens.

Glutamine alimentation in catabolic state

Glutamine should be reclassified as a conditionally essential amino acid in the catabolic state because the body's glutamine expenditures exceed synthesis and low glutamine levels in plasma are associated with poor clinical outcome. After severe stress, several amino acids are mobilized from muscle tissue to supply energy and substrate to the host. Glutamine is one of the most important amino acids that provide this function. Glutamine acts as the preferred respiratory fuel for lymphocytes, hepatocytes and intestinal mucosal cells and is metabolized in the gut to citrulline, ammonium and other amino acids. Low concentrations of glutamine in plasma reflect reduced stores in muscle and this reduced availability of glutamine in the catabolic state seems to correlate with increased morbidity and mortality. Adding glutamine to the nutrition of clinical patients, enterally or parenterally, may reduce morbidity. Several excellent clinical trials have been performed to prove efficacy and feasibility of the use of glutamine supplementation in parenteral and enteral nutrition. The increased intake of glutamine has resulted in lower septic morbidity in certain critically ill patient populations. This review will focus on the efficacy and the importance of glutamine supplementation in diverse catabolic states.

Glutamine supplementation in cancer patients receiving bone marrow transplantation and high dose chemotherapy

Glutamine supplementation of enteral and parenteral nutrition support has received increased attention in the research community over the past decade. Glutamine may become a conditionally essential nutrient during certain catabolic states, including after bone marrow transplantation (BMT). The administration of enteral or parenteral glutamine seems safe and also potentially efficacious in some patient groups undergoing intensive treatment for cancer. Studies indicate that adjunctive glutamine treatment may improve nitrogen retention, decrease clinical infection and length of hospital stay and reduce the incidence and severity of mucositis after BMT and high dose chemotherapy. Although not all studies demonstrate benefit, there are sufficient positive data to suggest that this nutrient should be considered in the metabolic support of many individuals undergoing the catabolic process of marrow transplantation. Given the available data, randomized, double-blind, controlled clinical trials of glutamine-enriched nutrition in patients receiving BMT and high dose chemotherapy protocols are indicated to further define the utility of this amino acid as adjunctive therapy. Studies of glutamine nutrition combined with current combinations of cytoreductive agents and hematopoietic growth factors in BMT will be particularly pertinent.

New developments in glutamine delivery

Numerous studies demonstrate that free glutamine can be added to commercially available crystalline amino acid-based preparations before their administration. Instability during heat sterilization and prolonged storage and limited solubility (35 g/L at 20 degrees C) hamper the use of free glutamine in the routine clinical setting. Indeed, there are many well-controlled and valuable trials with free glutamine, yet its use is restricted to clinical research. The obvious limitations of using free glutamine initiated an intensive search for alternative substrates. Synthetic glutamine dipeptides are stable under heat sterilization and highly soluble; these properties qualify the dipeptides as suitable constituents of nutritional preparations. Industrial production of these dipeptides at a reasonable price is an essential prerequisite for implications of dipeptide-containing solutions in clinical practice. Recent development of novel synthesis procedures allows increased capacity in industrial-scale production. Basic studies with synthetic glutamine-containing short-chain peptides provide convincing evidence that these new substrates are cleared rapidly from plasma after parenteral administration, without being accumulated in tissues and with negligible loss in urine. The presence of membrane-bound as well as tissue-free extracellular hydrolase activity facilitates a prompt and quantitative peptide hydrolysis, the liberated amino acids being available for protein synthesis and/or generation of energy. In the clinical setting, glutamine dipeptide nutrition beneficially influences outcome (nitrogen balance, immunity, gut integrity, hospital stay, morbidity and mortality). The provision of conditionally indispensable glutamine should be considered a necessary replacement of a deficiency rather than a supplementation. The beneficial effects observed with glutamine dipeptide nutrition should be seen simply as a correction of disadvantages produced by the inadequacy of conventional clinical nutrition. The availability of stable dipeptide preparations certainly facilitates, for the first time, adequate amino acid nutrition of critically ill, malnourished or stressed patients in the routine clinical setting and, thus, represents a new dimension in artificial nutrition.

Glutamine and cancer

Glutamine is the most abundant free amino acid in the human body; it is essential for the growth of normal and neoplastic cells and for the culture of many cell types. Cancer has been described as a nitrogen trap. The presence of a tumor produces great changes in host glutamine metabolism in such a way that host nitrogen metabolism is accommodated to the tumor-enhanced requirements of glutamine. To be used, glutamine must be transported into tumor mitochondria. Thus, an overview of the role of glutamine in cancer requires not only a discussion of host and tumor glutamine metabolism, but also its circulation and transport. Because glutamine depletion has adverse effects for the host, the effect of glutamine supplementation in the tumor-bearing state should also be studied. This communication reviews the state of knowledge of glutamine and cancer, including potential therapeutic implications.

Glutamine: commercially essential or conditionally essential? A critical appraisal of the human data

Glutamine is a nonessential amino acid that can be synthesized from glutamate and glutamic acid by glutamate-ammonia ligase. Glutamine is an important fuel source for the small intestine. It was proposed that glutamine is necessary for the maintenance of normal intestinal morphology and function in the absence of luminal nutrients. However, intestinal morphologic and functional changes related to enteral fasting and parenteral nutrition are less significant in humans than in animal models and may not be clinically significant. Therefore, it is unclear whether glutamine is necessary for the preservation of normal intestinal morphology and function in humans during parenteral nutrition. It was suggested that both glutamine-supplemented parenteral nutrition and enteral diets may pre-vent bacterial translocation via the preservation and augmentation of small bowel villus morphology, intestinal permeability, and intestinal immune function. However, it is unclear whether clinically relevant bacterial translocation even occurs in humans, much less whether there is any value in the prevention of such occurrences. Results of the therapeutic use of glutamine in humans at nonphysiologic doses indicate limited efficacy. Although glutamine is generally recognized to be safe on the basis of relatively small studies, side effects in patients receiving home parenteral nutrition and in those with liver-function abnormalities have been described. Therefore, on the basis of currently available clinical data, it is inappropriate to recommend glutamine for therapeutic use in any condition.

Free and protein-bound glutamine have identical splanchnic extraction in healthy human volunteers

The objectives of the present study were to determine the splanchnic extraction of glutamine after ingestion of glutamine-rich protein ((15)N-labeled oat proteins) and to compare it with that of free glutamine and to determine de novo glutamine synthesis before and after glutamine consumption. Eight healthy adults were infused intravenously in the postabsorptive state with L-[1-(13)C]glutamine (3 micromol x kg(-1) x h(-1)) and L-[1-(13)C]lysine (1.5 micromol x kg(-1) x h(-1)) for 8 h. Four hours after the beginning of the infusion, subjects consumed (every 20 min) a liquid formula providing either 2.5 g of protein from (15)N-labeled oat proteins or a mixture of free amino acids that mimicked the oat-amino acid profile and contained L-[2,5-(15)N(2)]glutamine and L-[2-(15)N]lysine. Splanchnic extraction of glutamine reached 62.5 +/- 5.0% and 66.7 +/- 3.9% after administration of (15)N-labeled oat proteins and the mixture of free amino acids, respectively. Lysine splanchnic extraction was also not different (40.9 +/- 11.9% and 34.9 +/- 10.6% for (15)N-labeled oat proteins and free amino acids, respectively). The main conclusion of the present study is that glutamine is equally bioavailable when given enterally as a free amino acid and when protein bound. Therefore, and taking into consideration the drawbacks of free glutamine supplementation of ready-to-use formulas for enteral nutrition, protein sources naturally rich in this amino acid are the best option for providing stable glutamine.

Glutamine and arginine: immunonutrients for improved health

There is considerable literature demonstrating that specific nutrients can influence immune function in health and disease. This review will examine the literature and the rational for classifying two amino acids, glutamine (gln) and arginine (arg), as "immunonutrients" during infections. An understanding of immune defenses during infections (virus, parasite, bacteria, protozoa) and metabolism of gln and arg by immune cells is necessary to understand how these nutrients can influence specific functions of the immune system. This review focuses on several key clinical studies in immunosuppressed individuals (burn patients, individuals with cancer and HIV infection, and those undergoing surgery or who have experienced major traumas) that have tested the hypothesis that the provision of gln and/or arg is beneficial to immune function and clinical outcome. These clinical studies support the dietary "essentiality" of these two nutrients for improving immune responses in most immunosuppressive states associated with high rates of infection. However, the role of these nutrients in modulating the immune changes that occur with exercise in healthy athletes demands additional experiments.

Nutritional support of the cancer patient: issues and dilemmas

Malnutrition in cancer patients results from multifactorial events and is associated with an alteration of quality of life and a reduced survival. A simple nutritional assessment program and early counselling by a dietitian are essential to guide nutritional support and to alert the physician to the need for enteral (EN) or parenteral nutrition (PN). A daily intake of 20-35 kcal/kg, with a balanced contribution of glucose and lipids, and of 0.2-0.35 g nitrogen/kg is recommended both for EN and PN, with an adequate provision of electrolytes, trace elements and vitamins. EN, always preferable for patients with an intact digestive tract, and PN are both safe and effective methods of administering nutrients. The general results in clinical practice suggest no tumor growth during nutritional support. The indiscriminate use of conventional EN and PN is not indicated in well-nourished cancer patients or in patients with mild malnutrition. EN or PN is not clinically efficacious for patients treated with chemotherapy or radiotherapy, unless there are prolonged periods of GI toxicity, as in the case of bone marrow transplant patients. Severely malnourished cancer patients undergoing major visceral surgery may benefit from perioperative nutritional support, preferably via enteral access. Nutritional support in palliative care should be based on the potential risks and benefits of EN and PN, and on the patient's and family's wishes. Research is currently directed toward the impact of nutritional pharmacology on the clinical outcome of cancer patients. Glutamine-supplemented PN is probably beneficial in bone marrow transplant patients. Immune diets are likely to reduce the rate of infectious complications and the length of hospital stay after GI surgery. Further studies are needed to determine the efficacy of such novel approaches in specific populations of cancer patients, and should also address the question of the overall cost-benefit ratio of nutritional pharmacology, and the effect of nutritional support on length and quality of life.

Is glutamine a unique fuel for small intestinal cells?

Although the small intestinal mucosa is designed to transport large quantities of all nutrients to the blood, the primary nutrients utilized by the enterocyte for growth and/or maintenance are quite restricted. The major fuels for the small intestinal mucosa are amino acids (glutamine, glutamate, aspartate), whereas glucose and fatty acids are of much less importance. Many of the experiments have been performed during growth or maintenance of mucosa in small rodents, especially the rat, a model in which the adaptation of the intestinal mucosa, at least to fasting, is quite different than in humans. A special role has been suggested for glutamine as a small intestinal fuel, compared with glutamate and aspartate, but the available data do not support this view. Clinical trials of glutamine supplementation suggest that, if glutamine has a role, it may be related to functions other than those relating to small intestinal function.