Some symptoms of stomach cancer can include fatigue, stomach pain, feeling full when only small amounts of food are consumed, and unintentional weight loss, states Mayo Clinic. Additionally, feeling bloated following a meal, nausea, indigestion or heartburn that is severe in nature can also be symptoms of stomach cancer.
There is more than one type of stomach cancer, according to Mayo Clinic. Cancer that begins in glandular cells is called an adenocarcinoma, while cancer that begins in immune system cells is referred to as lymphoma. Cancer that begins in cells that produce hormones is called a carcinoid tumor, and cancer that begins in nervous system tissue is a gastrointestinal stromal tumor. Most stomach tumors that are cancerous are adenocarcinomas. Carcinoid, lymphoma and gastrointestinal stromal tumors are rare types of stomach cancers.
While the exact cause of stomach cancer is not known, there is a strong relationship between a stomach cancer and a diet high in smoked, pickled and salted foods, explains Mayo Clinic. Stomach cancer rates worldwide are declining as more people use refrigeration. Cancer occurs when a mutation in the DNA of a cell or cells takes place. The cell divides very rapidly, living past the point that a normal cell dies. The accumulation of these cells forms a tumor.