Definition

A rare, inherited disorder in which many polyps (usually hundreds) form in the lining of the upper part of the stomach. Polyps are abnormal growths that may become cancer if they are not removed. People with GAPPS have an increased risk of developing a type of stomach cancer called intestinal gastric adenocarcinoma. This cancer begins in the mucus-producing cells in the innermost lining of the stomach. GAPPS is caused by certain mutations (changes) in a specific part of the APC gene. The age that people with one of these specific mutations in the APC gene develop GAPPS varies. Also called gastric adenocarcinoma and proximal polyposis of the stomach.