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CONCLUSIONS AS TO THE NATURE OF RODENT

CANCER.

It is not until after long observation of Rodent Cancer that the principal facts in its natural history can be collected. The changes are slow in progress, and in some respects peculiar; but the essential characters of it correspond, it appears to me closely, with those which distinguish any superficial Cancer. For it is not primarily an ulcer with an eroding edge, but rather an edge of a particular nature with a following ulcer. It is composed of a solid growth, which, having no limitation by a cyst, infilters among and supersedes the natural textures, which exhibits a power of continuous increase, and sometimes of forming a detached and not ulcerated nodule of the same disease, and which so far infects the adjoining parts that an incision, where they appear healthy, is yet followed by a return of the disease. The new growth in time degenerates and disappears, destroying with itself all the tissues which it had penetrated. Measured by the interval between its deposition and ulceration, the birth and death, so to speak, of any particular cell, the vitality of the growth is not less than that of ordinary Cancers; but in other respects, it appears to be composed of a more feebly vital material. For the slow rate of its increase prevents it from accumulating in so thick a mass as those which

grow faster than they die, and it is so little capable of a firm maintenance of life as to be rapidly removed by a transient erysipelas. Slow though it be, however, its power of growing is greater than that of the normal parts, being not arrested by any natural texture, and continuing and indeed increasing in its rate throughout the remainder of the patient's life. In accordance with its feeble vital energy, as compared with the more active malignant growths, the occasions are rare in which it imitates the cancerous character, by passing on to a subordinate lymphatic gland. The occurrence does sometimes happen, but the resemblance in dissemination never goes further, and the gland, however long enlarged and hardened, eventually softens or again subsides. Though the disease originates in skin, it is not limited to that texture, but corresponds with Cancer eminently in the particular faculty of indiscriminately invading all the tissues which it meets. Added to these, there are further indications of its cancerous nature in the occasional identity of its microscopic elements with those of the Epithelial Cancer and, since, so far as we know, it is never spontaneously curable, in its tendency to produce a fatal result.

An advantage of practical importance is gained in tracing the nature and alliances of this disease, when attention is thus withdrawn from the merely subordinate process of ulceration, and fixed upon the

substantial deposit. A yet greater advantage accrues, and one which is of value in the study of Cancer generally, when the unessential distinctions are disregarded, by which Cancer has been arbitrarily severed from other diseases, or when, at any rate, by a correct perception of its order and mechanism, the actual nature of its differences and its real alliances are discerned. The question, What constitutes Cancer? at one time capable of solution only in the disseminated stages of the disease, is now more early and more truly answered. But at the same time, the former notions of what is essential to it are much modified, as, on the one hand, it is perceived that the property of being conveyed alive to distant parts of the body, and there resuming growth, is found to be shared with Cancer by other active tumours, and, on the other hand, as certain tumours which never pass beyond their original site are recognised as Cancer by their local progress alone. In any given quality Cancer has its parallel with some other disease; and it has that quality, not because it is Cancer, but because it uses, in common with the disease which it resembles, some function in the body to which that quality is due. Many diseases infect glands besides Cancer, and for the same reason, that the lymphatic system equally serves them all. Pyæmic abscesses are as widely dispersed, and thus as constitutional, as the most general Cancer, for the

circulation is a highway alike in the one disease and in the other. And, if hereditariness proved a pre-existent tendency to Cancer before the outbreak of the first tumour, such tendencies are too common to prove Cancer constitutional. Warts, and cysts, and various innocent tumours, are as distinctly hereditary as Cancer sometimes is, and also, like Cancer, they may occur in one member only of a family there is nothing purely or essentially cancerous in the mere repetition of a disease in persons alike in their textures. So again with curability; other ailments, besides Cancer, will come again if they be imperfectly removed, and will thus pass for incurable with no better reason than Cancer. To characterise Cancer as incurable, or as originally a constitutional or necessarily a general or systemic disease, or as having for an essential quality the capacity of diffusing its elements into the adjoining lymphatic glands; to distinguish it by the greater proportion of its solid part as compared with its ulcer, or by its microscopic cell, would indeed separate it from the Rodent disease, but only by a catatomy which would also dissociate one recognised Cancer from another. Some of these misconceived distinctions will bear a little further discovery.

Curability constitutes but an accidental distinction between tumours, not one original and essential to their nature. Any tumour is incurable, so long as

the inadequate operations performed for the removal of it leave fragments behind which are capable of continued growth. The argument which would distinguish Cancer by our failure to eradicate it is applicable also to other tumours, even to fatty tumours, of which growing portions left in the tissues sometimes produce a third and a fourth recurrence.* That argument transfers to the disease a defect which, without fault in the Surgeon, really attaches to the operation.† Cancer and Rodent disease may both be locally eradicated. The distinction between them is in the facility of the extirpation, but though of great value in practical surgery, it is not decisive of an essential difference between them. Indeed, it is questionable on another ground, whether it be distinctive as a fact. The Rodent disease, at its commencement, may undoubtedly be extirpated, but in its later stages exemption from recurrence after apparently complete removal is less absolute than the usual success of operations would lead us to suppose. For the cicatrix may reopen, and without throwing up the distinct separate hard margin which characterises the ulcer in cutaneous texture, may ulcerate again widely. Should this fresh ulceration, however, arrive at skin again, the peculiar solid marginal rampart is reformed. Seemingly healthy parts

* De Morgan, Hulke, and Curling, Pathological Transactions, 1867. The Influence of Inadequate Operations on the Theory of Cancer. By Charles H. Moore. Medico-Chirurgical Transactions, 1867.