Gastric retention does not necessarily transform into cancer, and not all cancers have symptoms of gastric retention. There can be several cases as follows: 1. If the cause of gastric retention is pyloric obstruction or pyloric stenosis, and the cause of pyloric obstruction or stenosis is a benign ulcer or erosion, it can be completely healed after systematic and sufficient treatment and will not be transformed into a tumor at all. 2. If the above-mentioned ulcer is deeper, more difficult to heal or recurrent after healing, there is a risk of transformation into cancer. 3. If the cause of retention is a malignant ulcer, erosion or occupancy, it does not need to be transformed and is itself cancerous.