Table 1. National Cancer Institute's Common Terminology Criteria for Adverse Events: Diarrheaa,b continued...
In patients being treated for cancer, diarrhea is most commonly induced by therapy. Conventional methods of diarrhea-causing treatment include the following:
- Radiation therapy.
- Bone marrow transplantation.
Other causes of acute diarrhea include the following:
- Antibiotic therapy.
- Stress and anxiety associated with cancer diagnosis and treatment.
Typical infections are of viral, bacterial, protozoan, parasitic, or fungal etiology; they may also be caused by pseudomembranous colitis, a cause of diarrhea that often does not respond to treatment.Clostridium difficile is a common cause of pseudomembranous colitis.
Other causes of diarrhea in patients with cancer include the underlying cancer, responses to diet, or concomitant diseases (see Table 2). Common causes of diarrhea in patients receiving palliative care are difficulty adjusting the laxative regimen and impaction leading to leakage of stool around the fecal obstruction.
Another strategy for categorizing the causes of diarrhea is by putative underlying mechanisms. These include exudative (i.e., excess blood or mucous enters the gastrointestinal tract), malabsorptive, dysmotile, osmotic, and secretory (due to increased secretion of electrolytes and fluid—probably the mechanism underlying chemotherapy-induced diarrhea) factors or combinations of these factors.
Surgery, a primary treatment modality for many cancers, can affect the body by mechanical, functional, and physiological alterations. Postsurgical complications of gastrointestinal surgery affecting normal bowel function that may contribute to diarrhea include the following:[14,15]
- Increased transit time.
- Fat malabsorption.
- Lactose intolerance.
- Fluid and electrolyte imbalance.
- Dumping syndrome.
Certain chemotherapeutic agents can alter normal absorption and secretion functions of the small bowel, resulting in treatment-related diarrhea. Examples of chemotherapy agents with diarrhea-related potential are listed in Table 2. Patients receiving concomitant abdominal or pelvic radiation therapy or recovering from recent gastrointestinal surgery will often experience more severe diarrhea.
Radiation therapy to abdominal, pelvic, lumbar, or para-aortic fields can result in changes to normal bowel function. Factors contributing to the occurrence and severity of intestinal complications depend on the following:
- Total dose.
- Volume of bowel irradiated.
- Concomitant chemotherapy.
Common side effects of intestinal enteritis include the following: