Malignant tumour of the mucous membrane or glandular tissue of the stomach. Together with intestinal cancer this is one of the commonest malignant tumours. It affects men over the age of 40 in particular. The cause is not clear; a connection with the eating of salted or smoked fish is sometimes suggested. Stomach cancer has many symptoms in common with a stomach ulcer: pain, a ‘full’ feeling, nausea, vomiting, and loss of appetite and weight. Haemorrhage is a possible complication. An X-ray does not always distinguish between the two conditions either. Tests are made to distinguish between benign and malignant tumours; the simplest method is a barium contrast X-ray. A specialist should then be able to distinguish between an ulcer and a possibly malignant tumour. In young patients a clear case of stomach ulcer requires no further examination, but in older patients the possiblity of cancer should always be considered. Thus gastroscopy and the taking of biopsies for laboratory tests and cell analysis (cytology) are usually recommended. The last test is now considered the best, with almost 100 per cent accuracy. Certain circumstances are particularly suspect: if gastric acid production is low or absent (achlorhydria) when an ulcer is detected, then the chances are high that a malignant tumour is present. Ulcers that do not respond to normal treatment and recur persistently are also suspect, and so is chronic gastritis. Treatment of stomach cancer is by removal of the tumour and part of the stomach, to make sure that the cancer has all been taken out; surgery at an early stage reduces the likelihood of metastasis, emphasizing the importance of rapid and thorough examination. After surgery, care is taken that food can pass through the stomach again; for this purpose it may be necessary to make a connection between the stomach and a loop of the small intestine.