What are the potential causes of strictures in the gastrointestinal tract?

Location, location: The question is very broad and it would highly depend on which part of the GI tract we are talking about, i.e. The colon, the small intestine, the esophagus, etc. To give you a general framework though, i might say that some common causes are: cancer, ischemia (lack of blood supply), infection, inflammatory bowel disease (especially crohn's), radiation therapy, diverticulitis, and drugs.