The question as to what rôle is played by heredity in the causation of gastric cancer belongs to the etiological study of cancer in general. Probably in about 14 per cent. of the cases of cancer it can be determined that other members of the family are or have been affected with the disease.30 The influence of inheritance, therefore, is apparent only in a comparatively small minority of the cases. As suggested long ago by Matthew Baillie, this hereditary influence is better interpreted as in favor of a local predisposition (embryonic abnormality?) in the organ or part affected than in favor of the inheritance of a cancerous diathesis. It has been claimed by D'Espine, Paget, and others that cancer develops at an earlier age when there is a family history of the disease than when such history is absent.
30 This statement is based upon the collection of 1744 cases of cancer analyzed with reference to this question. Of these, a family history of cancer was determined in 243 cases. The cases are obtained from statistics of Paget and Baker, Sibley, Moore, Cooke, Lebert, Lafond, Hess, Leichtenstern, Von Winiwarter, and Oldekop. There is extraordinary variation in the conclusions of different observers upon this point. Velpeau asserted that he could trace hereditary taint in 1 in 3 cancerous subjects; Paget, in 1 in 4; Cripps, in 1 in 28. My conclusions agree with those obtained at the London Cancer Hospital (Cooke, On Cancer, p. 11, London, 1865).
The most remarkable instance of inherited cancer on record is reported by Broca (Traité des Tumeurs, vol. i. p. 151, Paris, 1866): 15 out of 26 descendants over thirty years of age of a woman who died in 1788 of cancer of the breast were likewise affected with cancer. As is well known, Napoleon the First, his father, and his sister died of cancer of the stomach.
It may be considered established that cancer sometimes develops in a simple ulcer of the stomach, either open or cicatrized. It is most likely to develop in large and deep ulcers with thickened edges, where complete closure by cicatrization is very difficult or impossible. It is difficult to prove anatomically that a gastric cancer has developed from an ulcer, and hence such statements as that of Eppinger, that in 11.4 per cent. of cancers of the stomach this mode of development existed, are of no especial value.31 No etiological importance can be attached to the occasional association of cancer with open or cicatrized simple ulcers in different parts of the same stomach. Of the comparatively few cases in which strict anatomical proof has been brought of the origin of cancer in simple gastric ulcer, probably the most carefully investigated and conclusive is one studied and reported by Hauser.32 It is, however, by no means proven that Hauser's view is correct, that cancer develops from the atypical epithelial growths often to be found in the cicatricial tissue of gastric ulcer. In a few instances both the clinical history and the anatomical appearances speak decisively for the development of cancer in a simple gastric ulcer;33 and the establishment of this fact is of clinical importance.
31 Prager Vierteljahrschr., vol. cxiv.
32 Das chronische Maqengeschwür, Leipzig, 1883, p. 61. See also Heitler, "Entwicklung von Krebs auf narbigen Grunde in Magen," Wien. med. Wochenschr., 1883, p. 961. It seems to me that at present there is a tendency to exaggerate the frequency with which cancer develops from gastric ulcer.
33 A particularly satisfactory case of this kind is reported by Lebert, op. cit., p. 503.
Many other factors in the causation of gastric cancer have been alleged, but without proof of their efficacy. This is true of chronic gastritis, which was once thought to be an important cause of gastric cancer, and is even recently admitted by Leube to be of influence.34 Certainly the majority of cases of cancer of the stomach are not preceded by symptoms of chronic gastritis. Although in a few instances gastric cancer has followed an injury in the region of the stomach, there is no reason to suppose that this was more than a coincidence.
34 In Ziemssen's Handb. d. spec. Path. u. Therap., Bd. vii. p. 134, Leipzig, 1878.
Few, if any, at present believe that depressing emotions, such as grief, anxiety, disappointment, which were once considered important causes of cancer, exert any such influence. Cancer of the stomach occurs as frequently in those of strong as in those of weak constitution—as often among the temperate as among the intemperate. If, as has been claimed (D'Espine), gastric cancer is relatively more frequent among the rich than among the poor, this is probably due only to the fact that a larger number of those in favorable conditions of life attain the age at which there is greatest liability to this disease. No previous condition of constitution, no previous disease, no occupation, no station in life, can be said to exert any causative influence in the production of gastric cancer.