From this table it appears that three-fifths of all gastric cancers occupy the pyloric region, but it is not to be understood that in all of these cases the pylorus itself is involved. In four-fifths of the cases the comparatively small segment of the stomach represented by the cardia, the lesser curvature, and the pyloric region is the part affected by gastric cancer. The lesser curvature and the anterior and the posterior walls are involved more frequently than appears from the table, inasmuch as many cancers assigned to the pyloric region extend to these parts. The fundus is the least frequent seat of cancer. In the cases classified as involving the greater part of the stomach the fundus often escapes.
78 These cases are collected from the following sources: Lebert, op. cit.; Prague statistics of Dittrich, Engel, Wrany, and Eppinger, loc. cit.; Habershon, op. cit.; Katzenellenbogen, op. cit.; and Gussenbauer and V. Winiwarter, loc. cit. Gussenbauer and V. Winiwarter assign to the class of cancers involving the whole stomach all cases which they found designated simply as carcinoma ventriculi without further description. This produces in their statistics an excessive number of cancers under this class. I have preferred, therefore, to estimate in their collection of cases the number of cancers involving the whole stomach, according to the percentage for this class obtained from the other authors above cited.
As was shown by Rokitansky, it is the exception for cancer of the pylorus to extend into the duodenum, whereas cancer of the cardia usually invades for a certain distance the oesophagus.
The varieties of carcinoma which develop primarily in the stomach are scirrhous, medullary, colloid, and cylindrical epithelial carcinoma.79 The distinction between scirrhous and medullary cancer is based upon the difference in consistence, the former being hard and the latter soft. Cylindrical-celled epithelioma cannot be recognized as such by the naked eye. It presents usually the gross appearances of medullary cancer. Soft cancer (including both cylindrical-celled epithelioma and medullary carcinoma) is the most frequent form of gastric cancer. Next in frequency is scirrhous cancer, and then comes colloid cancer, which, although not rare, is much less frequent than the other varieties.
79 I have not been able to find an authentic instance of primary melanotic cancer of the stomach, although this form is included by most authors in the list of primary gastric cancers. It is known that most cases formerly described as melanotic cancers are melanotic sarcomata, which originate usually in the skin or the eye and are accompanied frequently with abundant metastases. Secondary melanotic tumors have been several times found in the stomach. They were present in 7 out of 50 cases of melanotic cancer (or sarcoma) analyzed by Eiselt, although out of 104 cases not a single primary melanotic cancer occurred in the stomach (Prager Viertaljahrschr., vol. lxxvi. p. 54). The list of secondary melanotic sarcomata of the stomach might be still further increased. Of course gastric cancers colored by pigment from old blood-extravasations should not be confounded with melanotic tumors.
As all degrees of combination and of transition exist between the different forms of cancer, and as a large number of cancers of the stomach are of a medium consistence and would be classified by some observers as scirrhous and by others as medullary, statistics as to the relative frequency of the different varieties have very little value. Moreover, in most statistics upon this point there is no evidence that simple fibrous growths have not been confounded with scirrhous cancer, and as a rule little or no account is taken of cylindrical-celled epithelioma, which is a common form of gastric cancer—according to Cornil and Ranvier, the most common.80
80 For any who may be interested in such statistics I have collected 1221 cases of gastric cancer, of which 791 (64.8 per cent.) were medullary, 399 (32.7 per cent.) scirrhous, and 31 (2.5 per cent.) colloid. 22 cases described as epithelial have been included with the medullary; 29 cases described as fibro-medullary, and 1 as fasciculated, have been included with the scirrhous. The cases are from the previously-cited statistics of Lebert, Dittrich, Wrany, Eppinger, Gussenbauer, and V. Winiwarter, and from Fenger (Virchow u. Hirsch's Jahresbericht, 1874, Bd. i. p. 312).
Cancer of the stomach may grow in the form of a more or less complete ring around the circumference of the stomach, or as a circumscribed tumor projecting into the cavity of the stomach, or as a diffuse infiltration of the walls of the stomach. The annular form of growth is observed most frequently in the pyloric region. Cancerous tumors which project into the interior of the stomach are sometimes broad and flattened, sometimes fungoid in shape, but most frequently they appear as round or oval, more rarely irregular, crater-like ulcers, with thickened, prominent walls and ragged floor. The free surface of the tumor presents sometimes a cauliflower-like or dendritic appearance, which characterizes the so-called villous cancer. Diffuse cancerous infiltration is seated oftenest in the right half of the stomach, but it may occupy the cardiac region or even the entire stomach.
The relation of the cancerous growth to the coats of the stomach varies in different cases. The tumor usually begins in the mucous membrane and rapidly extends through the muscularis mucosæ into the submucous coat. In this lax connective-tissue coat the tumor spreads often more rapidly than in the mucous membrane, so that it may appear as if the cancer originated in the submucosa. The mucous membrane, however, is usually invaded, sooner or later, over the whole extent of the tumor. The dense muscular coat offers more resistance to the invasion of the tumor. Cancerous masses, however, penetrate along the connective-tissue septa between the muscular bundles, which often increase in number and size. In the muscular coat thus thickened can be seen the opaque white fibrous and cancerous septa enclosing the grayish, translucent bundles of smooth muscular tissue. Often, however, the whole muscular coat beneath the tumor is replaced by the cancerous growth, and can no longer be recognized. The serous and subserous connective tissue, like the submucous coat, offers a favorable soil for the growth of the tumor, which here appears usually in the form of large and small nodules projecting from the peritoneum. Adhesions now form between the stomach and surrounding parts, and opportunity is offered for the continuous growth of the cancer into these parts. In the manner described the tumor grows in all directions, sometimes more in depth, sometimes more laterally, sometimes more into the interior of the stomach.
Ulceration occurs in all forms of gastric cancer.81 The ulceration is caused either by fatty degeneration and molecular disintegration of the surface of the tumor or by the separation of sloughy masses. Doubtless the solvent action of the gastric juice aids in the process. The softer and the more rapid the growth of the cancer, the more extensive is likely to be the ulcer. Such ulcers are usually round or oval in shape, but their contours may be irregular from the coalescence of two or more ulcers or from serpiginous growth. The edges are usually high, soft in consistence, and often beset with polypoid excrescences. The floor is generally sloughy and soft, and often presents warty outgrowths. The edges and floor may, however, be hard and smooth. In the more slowly-growing scirrhous and colloid cancers the ulcers are more likely to be superficial. Partial cicatrization of cancerous ulcers may take place. The development of cicatricial tissue may destroy the cancerous elements to such an extent that only by careful microscopical examination can the distinction be made between cancer and simple ulcer or fibroid induration. The examination of secondary cancerous deposits in adjacent lymphatic glands or other parts becomes, then, an important aid in the diagnosis.