Intestinal structure and function in neoplastic disease

Catabolic outcome from non-gastrointestinal malignancy-related malabsorption leading to malnutrition and weight loss

PURPOSE OF REVIEW

Malnutrition of cancer patients is a significant cause of mortality and morbidity.

RECENT FINDINGS

The contributory factors in cancers anatomically involving the gastrointestinal tract are self-evident. However, how non-gastrointestinal malignancies affect gastrointestinal structure and function is not clear. The aim of this paper is to review the relationship between non-gastrointestinal malignancies and malabsorption, which leads to malnutrition, weight loss and increased mortality. In non-gastrointestinal cancer patients, intestinal morphological atrophy occurs, whereas in the jejunum absorption is impaired. Cytokines including IL-1 and TNF-alpha primarily induce delayed gastric emptying and also act directly on intestinal mucosa to induce malabsorption. These cytokines also directly act on several gastrointestinal hormones including cholecystokinin, neuropeptides including corticotropin-releasing factor, and via the vagus to decrease gastrointestinal motility.

SUMMARY

The combination of small intestine atrophy and delayed gastrointestinal motility are some of the reasons for malabsorption in cancer patients with non-gastrointestinal malignancies that contribute to the catabolic process.

General metabolic abnormalities in cancer patients: anorexia and cachexia

Cancer cachexia is a chronic wasting illness directly associated with the presence of uncontrolled malignancy. The authors discuss the various causes of inadequate nutrient intake, including the known data on anorexia, and outline the potential role of humoral factors as mediators of cachexia.

Malignancy, weight loss, and the small intestinal mucosa

The mucosal architecture and mucosal dynamics of the small bowel have been studied in patients with malignant disease not of the gastrointestinal tract but associated with severe weight loss. Mucosal changes in malignant disease are demonstrated by stereomicroscopy, mucosal architectural measurement, and decreased lactose utilization. Measurement of the epithelial DNA loss rate indicates, in association with mucosal measurement, that the architectural changes are caused by a hypoplasia of the epithelium. Similar findings are demonstrated in patients with profound weight loss due to other non-malignant wasting diseases. Although mucosal changes undoubtedly occur in malignant disease, the changes are not specific for malignancy and the concept of ;cancer enteropathy' is not tenable. It is suggested that mucosal changes are the effect of and not the cause of cachexia.