Nearly half of all cancer patients will receive radiation therapy as part of their treatment, according to the National Cancer Institute. High-energy radiation can kill or help control many kinds of cancer and is a mainstay of modern cancer treatment, along with chemotherapy and surgery. Unfortunately, radiation can damage or kill normal cells in your body and lead to early or late side effects. One possible late complication of abdominal or pelvic radiation therapy is abdominal adhesions, a type of fibrous scarring that can remain unrecognized until months or years later. Most people with abdominal adhesions do not have symptoms or other problems, but chronic pain or intestinal obstruction can occur.
Radiation Therapy
The high-energy radiation used in cancer radiotherapy kills cancer cells and shrinks tumors by damaging their genetic material, or DNA. This prevents the cells from multiplying normally, leading to slowed tumor growth and, eventually, death of the individual cells. The most common type of radiation therapy, known as external-beam therapy, is delivered from a device outside the body aimed at the cancer. Another common method, called brachytherapy, involves placing radioactive material directly inside the body at the site of the tumor. The type and dosage of radiation therapy for each patient is carefully planned and calculated by a cancer specialist called a radiation oncologist before treatment begins. These calculations take into account the type of cancer, its size, location, and nearby normal tissues that might be exposed. The doctor also factors in the patient’s medical history, health status and prior or future cancer treatments. The radiation oncologist’s goal is to maximize the radiation’s effect on the cancer while minimizing its effects on surrounding normal tissues.
Side Effects of Radiation Therapy
The DNA damage caused by radiation has its greatest effect on dividing cells, which makes rapidly growing cancer cells especially susceptible. Normal tissues that might be included in a treatment field vary in their sensitivity to radiation. The regularly dividing cells in hair follicles, skin, bone marrow and the inner lining of the intestines are most likely to be affected. The immediate or short-term side effects of radiation therapy -- hair loss, skin irritation, fatigue and nausea -- usually disappear after treatment ends. Late side effects, appearing months or years later, are difficult to predict and vary from person to person based on factors such as chemotherapy drugs also received, genetics and lifestyle risks such as smoking. Depending on the tissues exposed to radiation, complications can occur, such as intestinal damage with diarrhea or bleeding, memory loss, infertility, rare second cancers and fibrosis. Fibrosis is the medical term for scar tissue, which accumulates in areas of chronic inflammation or where large numbers of cells have died. With abdominal or pelvic radiation, this fibrosis can result in the development of abdominal adhesions.
Abdominal Adhesions
Abdominal adhesions are strands or areas of fibrosis that form between the abdominal walls and organs such as the intestines, stomach and liver. The abdominal cavity, which contains all of these organs, is normally covered by a slippery, moist lining that allows the organs to slide and shift smoothly around each other during body movements. When adhesions form, they often bridge across these organs, binding them together and preventing their normal movement. According to the National Digestive Diseases Information Clearinghouse, abdominal surgery is the most common cause of abdominal adhesions. They can also result from other causes such as appendicitis, abdominal infections, gynecologic infections and radiation treatments for cancer. Wherever the abdominal surface becomes irritated and inflamed, whether by surgery or radiation, scarring and adhesions can develop.
Complications of Adhesions
Most people with abdominal adhesions have no symptoms or trouble, and might be unaware that adhesions exist. When trouble does arise, the most common complaint is chronic abdominal or pelvic pain, which can be severe enough to feel like appendicitis or diverticulitis. Scarring of the ovaries or fallopian tubes can lead to infertility. The most serious complications from abdominal adhesions involve twisting and blockage of the intestines, which can lead to obstruction or death of a segment of bowel. The scar tissue in adhesions can cause tight kinks, bends or twists of different portions of the intestine, partially or completely obstructing the passage of stool and liquids, or cutting off the blood supply to the twisted segment. Symptoms include severe abdominal pain or cramps, vomiting, swelling of the abdomen, loud bowel sounds and the inability to have a bowel movement or pass gas. Complete obstruction or death of a segment of intestine, also known as a bowel infarction, are medical emergencies usually requiring surgery.
Diagnosis and Treatment
Abdominal adhesions might be suspected based on a history of prior pelvic or abdominal radiation therapy, chronic pain or symptoms of bowel obstruction. Physical examination is not usually helpful unless there are signs of intestinal obstruction or infarction. Neither X-rays nor ultrasound studies show uncomplicated adhesions well, although MRI studies are sometimes useful. Definitive diagnosis often requires looking inside the abdomen with a laparoscope or exploratory surgery, although distortion and abnormal bends in the intestine can sometimes be seen by colonoscopy. Liquid or low-residue diets, low in fiber and easily digestible, sometimes help relieve partial bowel obstructions, but the only way to remove symptomatic adhesions is with surgery. Breaking apart, or lysis of, adhesions can be performed by laparoscopic or open surgery, which carries the unfortunate risk of possibly creating more adhesions.
