In addition to the desirability of recognising a fatal disease as soon as possible, the recent advances which have been made in gastric surgery give ground for the hope that a malignant growth of the stomach might be removed with success if the operation is undertaken before infection of the structures outside the stomach has occurred. The question of ' early diagnosis ' has consequently become one of paramount importance, and numerous treatises have been published which purport to aid in its elucidation. Unfortunately, however, it would seem that their authors are more concerned with the early recognition of certain physical signs than of the disease from which they arise. Thus, the majority of writers still centre their attention upon the diagnostic importance of a tumour, and detail with the utmost minuteness the methods in vogue for its detection and differential diagnosis. But we have already endeavoured to show that a palpable tumour is absent in nearly one fifth of all cases of carcinoma of the stomach, and that its existence bears witness to the fact that the growth has given rise either to an extensive infiltration of the gastric wall or to a secondary infection of the great omentum and lymphatic glands. It is obvious, therefore, that while a tumour affords conclusive evidence of the existence of carcinoma, it also indicates that the disease has already existed for a considerable period of time and is too far advanced to admit of complete removal. Other authorities consider that the solution of the difficulty is to be found in the altered state of the gastric secretion, and affirm that an absence of free hydrochloric acid and the presence of a large quantity of lactic acid after a test meal are pathognomonic of the complaint. On the other hand, it has already been shown that not only are one or both these indications absent in about 10 per cent, of all the cases of gastric carcinoma, and that those neoplasms which originate in a simple ulcer usually exhibit an excess of hydrochloric acid, but that other diseases of the stomach are occasionally accompanied by similar changes in the secretion. Moreover, the chronic gastritis which is the immediate cause of the disappearance of the hydrochloric acid is itself only a secondary effect of the morbid growth, and seldom develops until either the pylorus has become contracted or the tumour has undergone superficial ulceration. It consequently follows that these chemical phenomena are at most merely confirmatory of the existence of the disease, and from the point of view of early diagnosis their value is strictly limited.
Nor does it seem that those who rely entirely upon the microscope are either more accurate in then conclusions or better able to recognise the complaint at an exceptionally early period of its development, since the Oppler-Boas bacillus does not appear in the contents of the stomach without the coexistence of lactic acid, while minute particles of growth or cells showing irregular mitoses are rarely, if ever, present in the washings of the organ unless the disease has invaded the mucous membrane. Lastly, it may be observed that some surgeons regard an exploratory laparotomy as the best method of diagnosis, while a few even advocate the operation in every case of dyspepsia that develops after middle age and fails to subside after six weeks of medical treatment. Apart from the inconvenience which the adoption of this suggestion would entail upon several millions of men and women who from various causes become the subjects of troublesome indigestion at this period of life, it has yet to be shown that digital exploration of the stomach is at any time a certain method of diagnosis. AU experience goes to show that even after death much difficulty is often experienced in distinguishing a localised carcinoma of the gastric wall from a simple ulcer or its scar; while a careful comparison of the conditions found at the autopsy with the apparent discoveries made at the operation in a large series of cases have convinced us that even the most experienced surgeons are very apt to confound the results of inflammation, of simple ulceration, and even of syphilis, with malignant growths of the stomach and duodenum. It must therefore be conceded that as a rule exploration of the stomach through an abdominal incision is not a method of diagnosis which can be recommended either for its simplicity or accuracy.
While it must be acknowledged that at the present time we do not possess any certain means of recognising the existence of carcinoma before it has infected the lymphatic glands, it is possible that in the future some chemical product of the morbid growth may be discovered in the secretion of the kidneys or in the saliva which will render the early diagnosis of the disease a matter of ease and certainty.