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Información sobre el tratamiento del cáncer incluyendo quirúrgica, quimioterapia, radioterapia, estudios clínicos, terapia con protón, medicina complementaria avanzadas.
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National Cancer Institute
Ultima Vez Modificado: 23 de agosto del 2004
Radiation enteritis is a functional disorder of the large and small bowel that occurs during or after a course of radiation therapy to the abdomen, pelvis, or rectum.
The large and small bowel are very sensitive to ionizing radiation. Although the probability of tumor control increases with the radiation dose, so does the damage to normal tissues. Acute side effects to the intestines occur at approximately 1,000 cGy. Because curative doses for many abdominal or pelvic tumors range between 5,000 and 7,500 cGy, enteritis is likely to occur. 1
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. 2 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. 3
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.
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 150 to 300 cGy. 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 proctitisincluding 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. 1
Patient examination and assessment of radiation enteritis should include the following: 2
Medical management includes treating diarrhea, dehydration, malabsorption, and abdominal or rectal discomfort. Symptoms usually resolve with medications, dietary changes, and rest. If symptoms become severe despite these measures, a treatment break may be warranted.
In addition to these medications, opioids may offer relief from abdominal pain. If proctitis is present, a steroid foam given rectally may offer relief from symptoms. Finally, if patients with pancreatic cancer are experiencing diarrhea during radiation therapy, they should be evaluated for oral pancreatic enzyme replacement, as deficiencies in these enzymes alone can cause diarrhea.
Damage to the intestinal villi from radiation therapy results in a reduction or loss of enzymes, one of the most important of these being lactase. Lactase is essential in the digestion of milk and milk products. Although there is no evidence that a lactose-restricted diet will prevent radiation enteritis, a diet that is lactose free, low fat, and low residue can be an effective modality in symptom management. 3
Only 5% to 15% of the patients who receive abdominal or pelvic irradiation will develop chronic radiation enteritis. Signs and symptoms include colicky abdominal pain, bloody diarrhea, tenesmus, steatorrhea, weight loss, and nausea and vomiting. Less common are bowel obstruction, fistulas, bowel perforation, and massive rectal bleeding. 1 The initial signs and symptoms occur 6 to 18 months after radiation therapy. Radiologic findings include submucosal thickening, single or multiple stenoses, adhesions, and sinus or fistula formation. 2 Microscopic findings include villi that are fibrotic or may be lost altogether. Ulceration is common, varying from simple loss of epithelial layers to ulcers that may penetrate to different depths of the intestinal wall, even to the serosa. Lymphatic tissue is often atrophic or absent. The submucosa is severely diseased. Arterioles and small arteries show profound changes, with hyalinization of the entire wall thickness. The muscularis is often distorted or focally replaced by fibrosis.
The diagnosis of chronic radiation enteritis may be difficult to make. Clinically and radiologically recurrent tumor needs to be ruled out. Because of the possible latency of the illness, it is essential that the physician obtain a detailed history of the patient's radiation therapy course. It is often advisable to include the radiation therapy physician in the continued management of the patient's care.
Medical management of the patient's symptoms (which are similar to symptoms of acute radiation enteritis) is indicated, with surgical management reserved for severe damage. 3 Fewer than 2% of the 5% to 15% of patients who received abdominal or pelvic radiation will require surgical intervention. 4
The timing and choice of surgical techniques remains somewhat controversial. A lower operative mortality (21% vs 10%) and incidence of anatomic dehiscence (36% vs 6%) have been reported with intestinal bypass than with resection. 5 6 Those who favor resection point out that the removal of diseased bowel decreases the mortality rate for resection and is comparable to the bypass procedure. 5 All agree that simple lysis of adhesions is inadequate and that fistulas require bypass.
Surgery should be undertaken only after careful assessment of the patient's clinical condition and extent of radiation damage because wound healing is often delayed, necessitating prolonged parenteral feeding after surgery. Even after apparently successful operations, symptoms may persist in a significant proportion of patients. 7
The PDQ® cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Editorial changes were made to this summary.
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This information is intended mainly for use by doctors and other health care professionals. If you have questions about this topic, you can ask your doctor, or call the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).
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