Tumours of the stomach may be classified as benign and malignant. The former are comparatively rare, and most of them are merely pathological curiosities. The latter constitute nearly 94 per cent. of all the tumours of the viscus met with on the post-mortem table, and more than 98 per cent. of those which can be detected during life. It is therefore advisable to consider, in the first place, those neoplasms which from their extensive growth and destructive character must be regarded as diseases of primary importance, and subsequently those which are either devoid of clinical interest, or at most are productive of symptoms of an obscure nature and of irregular occurrence.

It is usually the custom to describe a malignant tumour of the stomach as a ' carcinoma,' or ' cancer,' more or less qualified by terms which indicate some special physical feature of the growth. Of late years, however, the opinion has been steadily gaining ground that many cases which are regarded as examples of carcinoma are really sarcomatous in character, and at the present time there is sufficient evidence in favour of this view to warrant the inclusion of sarcoma as a special and important variety of malignant disease of the organ. Inasmuch as the duodenum is practically a prolongation of the stomach, the special features of carcinoma of this portion of the digestive canal also demand consideration.