By Dr. H. HENDERSON PATRICK, Glasgow. MR. CHAIRMAN, LADIES AND GENTLEMEN,
How to tackle the scourge of cancer is, without doubt, the most urgent problem which confronts the medical profession at the present time. For that reason, although this paper may not bring us much nearer the correct solution of the problem, I make no apology for introducing the subject. If I can afford you food for thought or matter for profitable discussion, or if I can enable some to view this subject from a new standpoint, the object of my discourse will be amply fulfilled.
The history of cancer I shall pass over. It was most ably and fully dealt with by our esteemed President, Dr. George Burford, in paper which he read at our Annual Congress in 1924. Suffice to say here that cancer is a disease of great antiquity, writings on the subject being traced back to 1500 B.C., and that there is no reason to suppose that during all those years the features of the disease have altered in any way.
Throughout those centuries the most astute brains in the medical profession have been endeavoring to discover the aetiology of and cure for this disease, and, during recent times at least, ample funds have been available for investigation (except, unfortunately, in homoeopathic circles), and yet no definite answers to the many questions with which the problem bristles have been forthcoming. Of theories there have been many, yet none has been supported by sufficient evidence to make it acceptable to the profession as a whole.
Let us refresh our memories regarding some of the generally accepted facts on the subject. The cancer growth consists of a mass of cells which, in appearance, are indistinguishable from the normal cells of the body. The cells may be of different types, but there is no type which is not normally found in the organism. They perform no useful function. They are not organized in any way, they seem to have one direction of function and one only, and that, proliferation. This has been described, very aptly I think, as an insanity of the tissue. The cells infiltrate the surrounding tissues, not through any special motor power which they possess, but entirely through mutual pressure due to their own multiplication, and their distribution takes the line of least resistance. They may enter the lymphatic channel or the blood-stream and so may reach adjacent or distant parts, carrying with them their power of proliferation.
In their new environment the same process is repeated, until, through time, by their parasitic action, their host is gradually destroyed. Since the masses of cells have no organization, the individual cells are easily killed, giving rise to neurotic areas, and ulceration often occurs. In these cases, septic poisoning or haemorrhage may be the immediate cause of death. The first evidence of the disease is always local. It begins in tissues which are, at the time, in a state of growth, or may be under repair, e.g., carcinoma, the more common form of malignant growth, originates in the epithelial or endothelial tissues, where throughout the whole of life a certain amount of tissue repair is normally in progress. Sarcoma, on the other hand, arises from the tissues derived from the embryonic mesoblast and is common only during the time of life when these tissues are in a state of growth.
Now, what is it that transforms this normal body cell into the cancer cell, into this insane cell which has lost all sense of co-ordination and seems to have only one property left, that of proliferation? All the writers on this subject seem to me to have the idea that the cancer cell has taken on some new life, has acquired some new ungovernable property which it did not previously possess. Is not this a wrong point of view? This power of reproduction is an intrinsic part of every cell during some part of the life of the organism as a potential element of many cells throughout the entire life of the organism.
During embryonic life cell proliferation must take place at a truly remarkable rate. When we recollect that the child at birth, plus the placenta, &c., have all developed in the short space of nine months from a single fertilized ovum, we must realize that the rate of cell proliferation is one with which few malignant growths could complete. Wherein lies the difference? The one is cell multiplication under guidance, and the other the same thing without any control.
Now, this “guidance” is a very wonderful thing. The fertilized ovum splits up into cells which soon become changed into various different kinds. There is continued growth and differentiation until all the various kinds of cells found in the body have been formed, after which cells, for the most part, produce their own kind only. The rate of growth of the various types of cell varies tremendously at different periods of the antenatal life. This guiding control, therefore, commands not only the type of growth, but also the rate of cell proliferation, increasing or decreasing it according to the needs of the organism.
What is this controlling influence? I doubt very much if mortal man will ever know. It is of the very essence of our spiritual existence. This cell control continues, also, throughout the entire life of the individual. We see it, for instance, in the repair of surface abrasion. The epithelial cells proliferate until the abrasion is healed and then proliferation stops. The control is still functioning. We see, then, that this power of reproduction is present in every cell during the period of growth, and in many cells, e.g., epithelial and endothelial, during the entire life of the individual.
Now I wish to suggest to you that the transition from the normal cell to the malignant is not due to any increased power which the cell has acquired, but is due to the breaking, for some reason, of that control under which all cells live and function, giving vent to that potential malignancy which is present in every cell. The earlier in the life of the individual the control is broken, the more potent is the latent power in the cell, hence the younger the victim of this disease, the more malignant, as a rule, is the growth.
Although it is highly improbable that we shall ever know the inner workings of the cell control, there is no reason, why, through time, we should not be able to tell with considerable accuracy the factors which lead to the severance of the bond between the cell and the higher influence. One factor is now fairly generally recognized, viz., the factor of local irritation. Evidence of this is found in chimney sweep’s cancer, cancer of the lip in clay-pipe smokers (probably due to heat), cancer of the tongue starting at the site of tooth irritation, cancer arising from continued exposure to X-rays. The common sites of cancer in the gastro-intestinal tract are just those parts where we would expect irritation to be most in evidence. Many other clinical examples might be given. In addition, we have the artificial production in animals of tumours very similar to cancer by local irritation. Taken altogether, the evidence that continued local irritation plays an important part in the breaking of the cell-controlling power is almost irresistible.
The ordinary effect of temporary local irritation is to stimulate the tissues to repair the damage done by the irritant. The higher control is slackened, the cells proliferate, and the repair is made good. If the irritation is continued the cell proliferation is continuous, the control is slackened to its utmost capacity and ultimately snaps. I use that expression as the nearest simile I can think of is that of an elastic band which will stretch so far and no further. Local irritation may be due, of course, to a great variety of causes. In addition to the examples already given, I would mention irritation surrounding long-standing simple ulceration; excessive stimulation following continued abuse of condiments, alcohol or drugs; chronic catarrh, e.g., of the cervix, uteri.
I think we may take it that local irritation, in one form or another, is the principal exciting factor in the breaking of this cell control. Local irritation, however, will not explain the incidence of cancer as we find it to-day. It does not explain the rapid increase in the death-rate from cancer within comparatively recent years. It does not explain why cancer is a disease affecting, more particularly, highly civilized countries. There must be obviously some predisposing cause or causes. I think one of the causes, at least, will be found in what I shall call, for want of a better term, general irritation. By general irritation I mean mental strain of various kinds. If you will go carefully into the history of your cases of cancer, you will find, in the vast majority of them, a history of mental strain, usually mental anxiety. That, at least, has been my experience. This mental strain is, in females, very often anxiety regarding friends or relatives, and, in the case of males, financial worries. Excess of work may also produce this suitable soil, but is much less likely to if it is not associated with worry.