GISTS are quite different from the other GI tumor types, such as stomach cancer and colon cancers. It occurs in specific nerve cells in the digestive system wall that play an important role in peristalsis, the movement of food through the GI tract. Half of the patients suffering from GISTS also suffer from the distant spread of the tumor via the bloodstream to other organs such as the liver and abdomen but rarely to the bones and lungs. Primarily, GIST cancer treatment depends upon the size and location of the tumor.