Radiation enteritis is inflammation of the intestine caused by radiation therapy.

Radiation enteritis is a condition in which the lining of the intestine becomes swollen and inflamed during or after radiation therapy to the abdomen, pelvis, or rectum. The small and large intestine are very sensitive to radiation. The larger the dose of radiation, the more damage may be done to normal tissue. Most tumors in the abdomen and pelvis need large doses of radiation. Almost all patients receiving radiation to the abdomen, pelvis, or rectum will have enteritis.

Radiation therapy to kill cancer cells in the abdomen and pelvis affects normal cells in the lining of the intestines. Radiation therapy stops the growth of cancer cells and other fast-growing cells. Since normal cells in the lining of the intestines grow quickly, radiation treatment to that area can stop those cells from growing. This makes it hard for tissue to repair itself. As cells die and are not replaced, gastrointestinal problems occur over the next few days and weeks.

Doctors are studying whether the order that radiation therapy, chemotherapy, and surgery are given affects how severe the enteritis will be.

Symptoms may begin during radiation therapy or months to years later.

Radiation enteritis may be acute or chronic:

• Acute radiation enteritis occurs during radiation therapy and may last up to 8 to 12 weeks after treatment stops.
• Chronic radiation enteritis may appear months to years after radiation therapy ends, or it may begin as acute enteritis and keep coming back.

The total dose of radiation and other factors affect the risk of radiation enteritis.

Only 5% to 15% of patients treated with radiation to the abdomen will have chronic problems. The amount of time the enteritis lasts and how severe it is depend on the following:

• The total dose of radiation received.
• The amount of normal intestine treated.
• The tumor size and how much it has spread.
• If chemotherapy was given at the same time as the radiation therapy.
• If radiation implants were used.
• If the patient has high blood pressure, diabetes, pelvic inflammatory disease, or poor nutrition.
• If the patient has had surgery to the abdomen or pelvis.

Acute and chronic enteritis have symptoms that are a lot alike.

Patients with acute enteritis may have the following symptoms:

• Nausea.
• Vomiting.
• Abdominal cramps.
• Frequent urges to have a bowel movement.
• Rectal pain, bleeding, or mucus in the stool.
• Watery diarrhea.
• Feeling very tired.

Symptoms of acute enteritis usually go away 2 to 3 weeks after treatment ends.

Symptoms of chronic enteritis usually appear 6 to 18 months after radiation therapy ends. It can be hard to diagnose. The doctor will first check to see if the symptoms are being caused by a recurrent tumor in the small intestine. The doctor will also need to know the patient's full history of radiation treatments.

Patients with chronic enteritis may have the following signs and symptoms:

• Abdominal cramps.
• Bloody diarrhea.
• Frequent urges to have a bowel movement.
• Greasy and fatty stools.
• Weight loss.
• Nausea.

Assessment of radiation enteritis includes a physical exam and questions for the patient.

Patients will be given a physical exam and be asked questions about the following:

• Usual pattern of bowel movements.
• Pattern of diarrhea:
  • When it started.
  • How long it has lasted.
  • How often it occurs.
  • Amount and type of stools.
  • Other symptoms with the diarrhea (such as gas, cramping, bloating, urgency, bleeding, and rectal soreness).
• Nutrition health:
  • Height and weight.
  • Usual eating habits.
  • Changes in eating habits.
  • Amount of fiber in the diet.
  • Signs of dehydration (such as poor skin tone, increased weakness, or feeling very tired).
• Stress levels and ability to cope.
• Changes in lifestyle caused by the enteritis.

Treatment depends on whether the radiation enteritis is acute or chronic.

Acute radiation enteritis

Treatment of acute enteritis includes treating the symptoms. The symptoms usually get better with treatment, but if symptoms get worse, then cancer treatment may have to be stopped for a while.

Treatment of acute radiation enteritis may include the following:

• Medicines to stop diarrhea.
• Opioids to relieve pain.
• Steroid foams to relieve rectal inflammation.
• Pancreatic enzyme replacement for patients who have pancreatic cancer. A decrease in pancreatic enzymes can cause diarrhea.
• Diet changes. Intestines damaged by radiation therapy may not make enough of certain enzymes needed for digestion, especially lactase. Lactase is needed to digest lactose, which is found in milk and milk products. A lactose-free, low-fat, and low-fiber diet may help to control symptoms of acute enteritis.
  • Foods to avoid:
    • Milk and milk products, except buttermilk, yogurt, and lactose-free milkshake supplements, such as Ensure.
    • Whole-bran bread and cereal.
    • Nuts, seeds, and coconut.
    • Fried, greasy, or fatty foods.
    • Fresh and dried fruit and some fruit juices (such as prune juice).
    • Raw vegetables.
    • Rich pastries.
    • Popcorn, potato chips, and pretzels.
    • Strong spices and herbs.
    • Chocolate, coffee, tea, and soft drinks with caffeine.
    • Alcohol and tobacco.
  • Foods to choose:
    • Fish, poultry, and meat that are broiled or roasted.
    • Bananas.
    • Applesauce and peeled apples.
    • Apple and grape juices.
    • White bread and toast.
    • Macaroni and noodles.
    • Baked, boiled, or mashed potatoes.
    • Cooked vegetables that are mild, such as asparagus tips, green and waxed beans, carrots, spinach, and squash.
    • Mild processed cheese. Processed cheese may not cause problems because the lactose is removed when it is made.
    • Buttermilk, yogurt, and lactose-free milkshake supplements, such as Ensure.
    • Eggs.
    • Smooth peanut butter.
  • Helpful hints:
    • Eat food at room temperature.
    • Drink about 12 eight-ounce glasses of fluid a day.
    • Let sodas lose their fizz before drinking them.
    • Add nutmeg to food. This helps slow down movement of digested food in the intestines.
    • Start a low-fiber diet on the first day of radiation therapy.

Chronic radiation enteritis

Treatment of chronic radiation enteritis may include the following:

• Same treatments as for acute radiation enteritis symptoms.
• Surgery. Few patients need surgery to control their symptoms. Two types of surgery may be used:
  • Intestinal bypass: A procedure in which the doctor creates a new pathway for the flow of intestinal contents around the damaged tissue.
  • Total intestinal resection: Surgery to completely remove the intestines.
  Doctors look at the patient's general health and the amount of damaged tissue before deciding if surgery will be needed. Healing after surgery is often slow and long-term tubefeeding may be needed. Even after surgery, many patients still have symptoms.