Gastrointestinal radiation injury: Symptoms, risk factors and mechanisms

Table 3 Acute and chronic manifestations of gastrointestinal radiation injury

Clinical manifestations	Radiation tolerance doseTD5/5, TD50/5 (Gy)	Gastrointestinal organ
Oral mucositis occurs in > 90% of patients with concurrent chemotherapy[40]	Parotid gland: TD5/5 (32) TD50/5 (46)[60,179,180]	Mouth, salivary glands, hypopharynx, parotid
Xerostomia and altered saliva composition
Acute Grade 3-4 oesophageal injuries occur in 46%with concurrent chemotherapy[181]	TD5/5 (55-60)
Dose > 58 Gy predicts Grade 3-5 acute oesophagitis[54]	TD50/5 (68-72)[60,179]	Oesophagus
60 Gy resulted in Grade 3 toxicity in 42%[182]
Radiation can lead to late stricture and/or perforation of the oesophagus[53,60]
40 Gy: Severe late toxicity in 7% including ulceration, gastritis and small-bowel obstruction/perforation[183]	TD5/5; (50-60) TD50/5 (65-70)[60,179]	Stomach
Elevated liver enzymes in 5%[184]	TD5/5; (30-50)	Liver Small intestine
(31.3-37 Gy resulted in RILD in 9.4%[66,185]	TD50/5; (40-55)[60,179]
45 Gy cause 5% Grade 3-4 toxicity and 14% with concurrent chemotherapy[71]	TD5/5; (40-50)
Diarrhoea, abdominal pain in 20-70%[72]	TD50/5; (55-60)[60,179,180]
Transmural fibrosis leading to obstruction in 5%-10%[68,77-78]
Intestinal fistulation occurs at a rate of 0.6% to 4.8%[68,79]		Colon and rectum
50 Gy 5 year estimate of small bowel obstruction is 11%[186]
Colitis in 25%-50% of patients[186]	Colon
Grade 2-3 acute proctitis 40%[91]	TD5/5; (45-55)
Chronic rectal symptoms in 6.7%-31%[91]	TD50/5 (55-65)[60,179,180]
Acute symptoms of anus and rectal injury occur in up to 75% of patients during radiotherapy[187]	Rectum
	TD5/5; (60-61.38)
	TD50/5 (80-81.38)[60,179,180]

TD5/5: Radiation dose associated with 5% of patients’ risk of delayed toxicity in 5 years; TD50/5: The radiation dose associated with 50% of patients’ risk of delayed toxicity in 5 years. RILD: Radiation-induced liver disease.