Enteritis is an inflammation of the intestine; the term applies chiefly to the small intestine. In the context of cancer, enteritis is a functional disorder of the large and small bowel that occurs as a result of radiation therapy applied to the abdomen, pelvis, or rectum. It occurs at the onset of radiation therapy (acute radiation enteritis) and may also reappear after completion of the radiation treatment (chronic enteritis).
Causes
Radiation enteritis occurs because the large and small intestines are sensitive to all forms of ionizing radiation. Some areas of the gastrointestinal tract are more sensitive to radiation than others; the colon is more sensitive to the effects of radiation than the small intestine, for example. Although the probability of tumor control increases with the radiation therapy dose, so does the probability of damage to normal, healthy tissues. Since the doses required to destroy many tumors are very high, acute side effects to the intestines also occur, chief among which is enteritis. Thus, the majority of patients undergoing radiation to the abdomen, pelvis, or rectum will show signs of acute enteritis.
Symptoms of the disorder are observed during the first course of radiation treatment and take about eight weeks to become acute. Chronic radiation enteritis may also occur months to years after a patient has undergone a course of radiation therapy. The symptoms include colicky abdominal pain, bloody diarrhea, tenesmus, weight loss, nausea and vomiting, bowel obstruction and rectal bleeding, sometimes very severe.
Several factors influencing the occurrence and extent of radiation enteritis have been identified. They include the dose of radiation given to the patient, the size of the tumor being treated, the concomitant prescription of chemotherapy and the general state of the patient's health. For example, enteritis will be more severe in patients with a history of hypertension, diabetes or inadequate nutrition.
Treatments
Some symptoms of radiation enteritis are caused by an overgrowth of bacteria, and, in these cases, antibiotics may be prescribed. Patients who develop acute enteritis report nausea, vomiting, abdominal cramping, and diarrhea. Diarrhea impairs the digestive and absorptive functions of the gastrointestinal tract, resulting in malabsorption of fat, lactose, bile salts, and vitamin B12. Patients also complain about rectal pain and bleeding.
Treatment of acute enteritis accordingly includes treating diarrhea, dehydration and abdominal and rectal pain or discomfort. Antidiarrheal drugs are usually prescribed, such as Kaopectate, Lomotil, Paregoric or Imodium. Additionally, bile salt-retaining drugs may also be indicated, such as cholestyramine. Bowel cramps may be alleviated with antispamodic drugs, such as Donnatal.
Approximately 5%-10% of patients having received radiation therapy for abdominal or pelvic cancers develop chronic enteritis. In some cases, surgery may be indicated. There is at present no agreement as to the proper timing and choice of surgical intervention in such cases. Surgery is thus only undertaken after careful assessment of individual patient conditions and health status.
Surgery may also be indicated for patients who have developed radiation enteritis-induced strictures. (Strictures are narrowing of passages or canals.)
An important complementary therapy is nutrition management. Another side effect of radiation is to destroy the intestinal villi, which impairs the body's capacity to absorb nutrients and also destroys enzymes required for digestion, such as lactase, required to digest milk and dairy products. Thus a lactose-free diet is often recommended.
Besides milk and dairy products, it is often recommended to avoid foods such as whole bran bread and cereals, nuts, seeds and coconuts, fried and greasy foods, fruit and some fruit juices (prune juice especially), uncooked vegetables, potato chips, pretzels, strong spices and herbs, chocolate, coffee, tea, alcohol and tobacco.
Recommended foods include fish, poultry, and cooked, broiled, or roasted meat, bananas, apple sauce, peeled apples, apple and grape juices, white bread, noodles, baked, boiled, or mashed potatoes, cooked vegetables such as asparagus tips, green and waxed beans, carrots, spinach, mild processed cheese, eggs, smooth peanut butter, buttermilk, yogurt and nutmeg.
Additionally, it is recommended to ingest food at room temperature and to drink plenty of water every day. Carbonated sodas should be allowed to lose their carbonation prior to drinking.
Monique Laberge, Ph.D.
Acute
—Medical condition which has a short and relatively severe course.
Chronic
—Medical condition persisting over a long period of time.
Gastrointestinal tract
—The gastrointestinal tract starts with the oral cavity (mouth) and proceeds to the esophagus, the stomach, the duodenum, the small intestine, the large intestine, the rectum and the anus.
Intestinal villi
—Microscopic finger-like projections located on the lining of the small intestine which are responsible for the absorption of nutrients.
Ionizing radiation
—Radiation sufficiently energetic so as to remove electrons from an atom. Examples are x rays, gamma rays, beta radiation (electrons) and alpha radiation (helium nuclei) as well as the radiation emitted by heavier elements. The higher the energy of ionizing radiation, the more likely the tissue or cell damage.
Lactose
—The major sugar present in human and bovine milk.
