In stage 0, abnormal cells are found in the mucosa (innermost layer) of the stomach wall. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ. Stage IA: Cancer has formed in the mucosa (innermost layer) of the stomach wall and may have spread to the sub mucosa (layer of tissue next to the mucosa). Stage IB: Cancer: has formed in the mucosa (innermost layer) of the stomach wall and may have spread to the sub mucosa (layer of tissue next to the mucosa). Cancer has spread to 1 or 2 nearby lymph nodes or has formed in the mucosa of the stomach wall and has spread to the muscle layer.
