Definition

Stage I is divided into stages IA and IB. In stage IA, cancer has formed in the mucosa (innermost layer) of the stomach wall and may have spread to the submucosa (layer of connective tissue between the mucosa and the muscle layer). In stage IB, cancer (1) has formed in the mucosa of the stomach wall and may have spread to the submucosa and has spread to 1 or 2 nearby lymph nodes; or (2) has formed in the mucosa of the stomach wall and has spread to the muscle layer. Also called stage I gastric cancer.