Coeliac disease
Coeliac disease presents the strongest associations to gastrointestinal and lymphoproliferative cancers. In coeliac disease, the autoimmune reaction is caused by the body's loss of immune tolerance to ingested gluten, found primarily in wheat, barley, and rye. This explains the increased risk of gastrointestinal cancers, as the gastrointestinal tract includes the esophagus, stomach, small intestine, large intestine, rectum, and anus, all areas that the ingested gluten would traverse in digestion. The incidence of gastrointestinal cancer can be partially reduced or eliminated if a patient removes gluten from their diet. Additionally, celiac disease is correlated with lymphoproliferative cancers.