Table 5.

All-grade adverse events of gastrointestinal origin in cancer patients treated with ICI [71, 74–81]

System	Organ	Symptoms	Abnormalities in diagnostic test results	Suspected pathology
Digestive system	Intestines	Diarrhea Abdominal pain Nausea Cramping Blood/ mucous in stools Changes in bowls habits Fever Abdominal distention Obstipation Constipation Dehydration Electrolyte imbalance	Blood test (anemia, elevated CRP, leukocytosis, hypoalbuminemia) Infectious workup (stool culture, Clostridium difficile, CMV serologies) Inflammatory markers (fecal leukocytes/lactoferrin/fecal calprotectin) Fecal occult blood test (FOBT) Lactoferrin—as an indicator of patients requiring urgent colonoscopy Calprotectin—shows activity of the disease Colonoscopy (normal mucosa/ mild erythema, severe inflammation with mucosal granularity, ulceration, luminal bleeding, erosions) Mucosal biopsy (lamina propria expansion, villous blunting, acute inflammation) CT imaging FDG-PET-CT	Colitis
	Liver	Yellowing of skin/whites of the eye Nausea/vomiting Pain on the right side of the abdomen Drowsiness Dark urine Bleeding or bruise more easily Feeling less hungry Fever Fatigue Malaise Hypersomnia	Elevation of serum levels of hepatic alanine/aspartate aminotransferase, GGTP, and ALP Elevated bile USG/CT/MRI Liver biopsy (portal and periportal inflammation, hepatocellular necrosis with infiltrating lymphocytes, plasma cells, and eosinophils) Coagulation disorders HIV, hepatitis A and B, blood quantiferon for tuberculosis—to prepare patients to start infliximab	Hepatitis
	Pancreas	Abdominal pain Nausea/vomiting Fever Fatigue	Increase of pancreatic enzymes (amylase, lipase) CT (swollen pancreas, reduced tissue contrast enhancement, lobulation) FDG-PET-CT (increased FDG uptake)	Pancreatitis