Cancer Health Center

Etiology

Almost all patients undergoing radiation to the abdomen, pelvis, or rectum will show signs of acute enteritis. Injuries clinically evident during the first course of radiation and up to 8 weeks later are considered acute.[1] Chronic radiation enteritis may present months to years after the completion of therapy, or it may begin as acute enteritis and persist after the cessation of treatment. Only 5% to 15% of persons treated with radiation to the abdomen will develop chronic problems.[2]

Factors that influence the occurrence and severity of radiation enteritis include the following:

1. Dose and fractionation.
2. Tumor size and extent.
3. Volume of normal bowel treated.
4. Concomitant chemotherapy.
5. Radiation intracavitary implants.
6. Individual patient variables (e.g., previous abdominal or pelvic surgery, hypertension, diabetes mellitus, pelvic inflammatory disease, inadequate nutrition).[3,4]

In general, the higher the daily and total dose delivered to the normal bowel and the greater the volume of normal bowel treated, the greater the risk of radiation enteritis. In addition, the individual patient variables listed above can decrease vascular flow to the bowel wall and impair bowel motility, increasing the chance of radiation injury.

Acute Radiation Enteritis

Diagnosis

Radiation therapy exerts a cytotoxic effect mainly on rapidly proliferating epithelial cells, like those lining the large and small bowel. Crypt cell wall necrosis can be observed 12 to 24 hours after a daily dose of 1.5 to 3 Gy. Progressive loss of cells, villous atrophy, and cystic crypt dilation occur in the ensuing days and weeks. Patients suffering from acute enteritis may complain of nausea, vomiting, abdominal cramping, tenesmus, and watery diarrhea. With diarrhea, the digestive and absorptive functions of the gastrointestinal (GI) tract are altered or lost, resulting in malabsorption of fat, lactose, bile salts, and vitamin B₁₂. Symptoms of proctitis-including mucoid rectal discharge, rectal pain, and rectal bleeding (if mucosal ulceration is present)-may result from radiation damage to the anus or rectum.

Acute enteritis symptoms usually resolve 2 to 3 weeks after the completion of treatment, and the mucosa may appear nearly normal.[5]

Assessment

Patient examination and assessment of radiation enteritis should include the following:[6]

1. The usual pattern of elimination.
2. The pattern of diarrhea, including the following:
   1. Onset.
   2. Duration.
   3. Frequency, amount, and character of stools.
   4. Presence of other symptoms such as flatus, cramping, nausea, abdominal distension, tenesmus, bleeding, and rectal excoriation.
3. The nutritional status of the patient, including the following:
   1. Height and weight.
   2. Usual eating habits, any change in eating habits, and amount of residue in diet.
   3. Signs of dehydration such as poor skin turgor, serum electrolyte imbalance, increased weakness, or fatigue.
4. Present level of stress, coping patterns, and impact of signs and symptoms of enteritis on usual lifestyle patterns.

Medical management