A tumor in the stomach may be the result of stomach or gastric cancer, according to WebMD. However, there are some known instances of benign stomach tumors.
The American Cancer Society estimates that about 22,000 cases of stomach cancer are diagnosed annually, and over 10,000 people die every year of the disease. The most common type of stomach cancer is adenocarcinoma, which accounts for 90 to 95 percent of all cases.
The National Center for Biotechnology Information reports that benign tumors of the stomach are not common and constitute only 5 to 10 percent of all stomach tumors. Furthermore, benign lesions or tumors may become malignant in time.