The Erasmus Wilson lectures on the general pathology of tumours : delivered before the Royal College of Surgeons of England on February 10th, 12th, and 14th, 1902 / by Charles Powell White.

White, Charles Powell, 1867-1930.

Date:: [1902]

Credit: The Erasmus Wilson lectures on the general pathology of tumours : delivered before the Royal College of Surgeons of England on February 10th, 12th, and 14th, 1902 / by Charles Powell White. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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$Extrinsic Causes. Causal factors may be divided into those which are of extrinsic and those which are of intrinsic origin. When we speak of a disease as a whole the term extrinsic implies that the factor is derived from outside the body ; when, however, a disease is considered in its relation to any particular organ the term implies that the causal factor is derived from outside that organ, but not necessarily from outside the body. Extrinsic factors undoubtedly play an important part in the causation of tumour formation. Tumours may arise as a result of chronic irritation such as that produced by constant friction or by the presence of a chronic ulcer ; they have also been ascribed to a blow or sudden injury as in the case of a sarcoma arising at the site of a fracture in a bone. These extrinsic factors, which are known by the general term irritants, are also the exciters of inflammatory pro- cesses, but there is this difference betw.een the two cases. When inflammation follows the action of an irritant the amount of inflammation depends on the amount of irritation and on removing the irritant the inflammatory process ceases and the injury is made good ; in the case of a tumour following the action of an irritant, on the other hand, the action of the irritant may be momentary while the growth of the tumour is prolonged and the removal of the irritant does not cause the cessation of the tumour growth. These extrinsic factors, therefore, cannot be the essentia] causal factors of tumour formation and can only be remote factors which act through the medium of intermediate intrinsic factors. We must, however, consider the possibi'ity of the existence of a special extrinsic factor, such as an animal or vegetable parasite. The theory of parasitic causation of tumour formation has gained a large amount of acceptance at the present time and, indeed, almost all those who are working at the subject are approaching it from this point of view. This theory is only supposed to apply to those tumours which are malignant, but it is equally neces- sary to explain the formation of simple tumours if an extrinsic factor is thought to be essential at all, because the con- tinuous and increasing growth of the tumour demands a con- tinuous and increasing causal factor. I myself have not engaged in the search for a parasite although I have seen the bodies claimed to be of that nature. I have, however, studied minutely the histology and general pathology of tumours with a view to determining whether or not tumour formation can be explained by this theory and I have come to the conclusion that the essential causal factor cannot be found in any extrinsic irritant, whether parasitic or not. On account of the importance of this theory it is necessary to examine it closely and carefully to consider the arguments on both sides. In the following remarks I shall, for the sake of simplicity, use the term carcinoma, but the arguments will, as a rule, equally apply to sarcoma.$