Table 1. National Cancer Institute's Common Terminology Criteria for Adverse Events: Diarrheaa,b continued...
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]
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:
Acute intestinal side effects occur at approximately 10 Gy and may last up to 8 to 12 weeks posttherapy. Chronic radiation enteritis may present months to years after completion of therapy and necessitates dietary modification and pharmacological management and, in some instances, surgical intervention. (Refer to the Radiation Enteritis section of this summary for more information.)
Graft-versus-host disease (GVHD) is a major complication of allogeneic transplantation, and the intestinal tract, skin, and liver are commonly affected. Symptoms of gastrointestinal GVHD include nausea and vomiting, severe abdominal pain and cramping, and watery, green diarrhea. The volume of accompanying GVHD-associated diarrhea may reach up to 10 L per day and is an indicator of the degree and extent of mucosal damage. Acute GVHD is usually manifested within 100 days posttransplant, although it can occur as early as 7 to 10 days posttransplant. It may resolve or develop into a chronic form requiring long-term treatment and dietary management.