Stomach cancer. Coloured transmission electron micrograph (TEM) of a section through an adenocarcinoma of the stomach. Malignant cuboidal cells with microvilli are present. Adenocarcinomas are cancers that arise from glandular tissue in the lining of an organ. This is the most common type of stomach cancer. Its main risk factors are a diet high in salt, infection with the bacteria Helicobacter pylori and smoking. Symptoms include indigestion, pain, difficulty swallowing and nausea or vomiting. Treatment is with surgery to remove the tumour, combined with chemotherapy. Human tissue. Magnification: x2'500 when printed at 10 centimetres wide.