Table 2.

RTOG/EORTC radiation toxicity grading system for lower gastrointestinal tract

	Grade 1	Grade 2	Grade 3	Grade 4
Early radiation toxicity (< 6 mo post radiotherapy)	Increased frequency of bowel movements not requiring medical therapy	Increased frequency of bowel movements requiring medication or causing abdominal pain	Diarrhoea requiring IV treatment, mucous or bloody discharge PR, abdominal distention	Acute/subacute bowel obstruction, fistula formation, GI bleed requiring transfusion, abdominal pain requiring tube decompression
Late radiation toxicity (> 6 mo post radiotherapy)	Bowel movements of 5 per day, mild abdominal cramping, mild PR bleeding	Bowel movements > 5 per day, increased mucous PR, intermittent PR bleeding	Obstruction or bleeding requiring operative management	Necrosis, perforation, fistula formation

PR: Per rectum; IV: Intravenous; GI: Gastrointestinal.