Acute and Chronic Gastrointestinal Side Effects of Radiation Therapy
Early and late GI organ injury may occur following irradiation of thoracic, abdominal, and pelvic malignancies of GI and non-GI origin. As with all toxicities associated with radiation therapy, GI side effects are categorized broadly into 2 types: early or acute reactions, such as diarrhea and nausea, which can occur during and soon after completion of a treatment course, and late or chronic effects, such as ulceration, stricture formation, and bowel obstruction, which can develop months to years later. Severe acute reactions can lead to treatment breaks and, in turn, a suboptimal treatment course, whereas the concern for chronic toxicity, particularly to the small bowel, is commonly a dose-limiting consideration in the creation of a treatment plan. The incidence and severity of radiation-induced morbidity depends on total dose and fraction size, treatment volumes and techniques, the presence or absence of other modalities such as systemic therapy and surgery, and any underlying patient comorbidities. This chapter discusses the early and late toxicities of RT and combined chemoradiation regimens to the esophagus, stomach, small and large intestines, rectum, anus, pancreas, and liver.
