THE INCREASE OF CANCER

AMONG the maladies which affect the human race there are three classes which are so largely responsible for premature death that they are not only to be looked upon as subjects of interest and discussion among medical men, but must be recognised as matters of grave national concern. For this reason the zymotic and tuberculous diseases have long engaged the attention of the statesman as well as of the general public, and much has already been done to identify the causes and to diminish the insanitary conditions which lead to their occurrence, so that many of them can now be classed under the title of preventable disease.

Recently attention has been directed to the third class-the group known under the generic term of malignant growths'—and it may not unreasonably be hoped that a closer study of the conditions under which these arise may lead, in this case also, to methods of prevention, if not of cure.

The steady increase in the mortality from cancer during the last thirty years is one of the most remarkable phenomena in the history of medicine. In England the death-rate from cancer, which was in 1890, 67 6, had in 1900 risen to 82.8 per 100,000 living; an increase in round numbers of 4,500 in the annual total of deaths from this disease.

The following figures show more exactly the bearing of this death-rate :

It will be seen that the disease caused nearly one in twenty of the whole number of deaths in the year, and rather more than one in twelve of the deaths of those over thirty-five; in 1890 the proportion of the latter was only one in twenty.

The steady yearly increase in the mortality from cancer is the more striking from the fact that it has manifested itself at a period during which hygienic conditions have in every way improved.

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Moreover, the great advances of surgery during the same time have enabled operations for the removal of the disease never before undertaken to be performed with success. From this point of view it would, therefore, appear that the increase of the disease has been even greater than the larger mortality would indicate.

The constant growth of the proportion of deaths from malignant disease which has been observed in England is equally noticeable in Ireland, which has always had a comparatively low cancer mortality, but where the recent increase has been great enough to induce the Registrar-General to issue a special report on the subject. Further, it is not in the United Kingdom alone that the death-rate from this terrible disease grows steadily year by year; the same phenomenon is exhibited in almost every other country in the world. This is shown by the following table, which gives the death-rate from cancer in 1890 and 1900 in the countries named:

Death-rate from Cancer per 100,000 Living.

The above figures, showing a growth of more than 30 per cent. in a period of ten years, cannot but be extremely alarming, and lead to the impression that if the rising tide cannot be checked cancer will, within a measurable period, be as great a scourge as the worst plagues of the Middle Ages.

It must, however, be admitted that it is doubtful whether there has been a real increase in the number of deaths quite as large as the comparative rates would lead us to suppose. Three facts have been suggested which may go to explain the larger figure which appears opposite to the heading 'Deaths from Cancer.' First, it is said that the older statistics were extremely imperfect; secondly, that the mortality from other diseases is now less than formerly, and therefore more survive to the later periods of life; thirdly, that improved methods of diagnosis have enabled many cases to be identified which were not formerly classed as cases of cancer. The first two points appear to be of little value. The statistical errors would probably not be all in one direction; nor does there appear to have been any sufficient increase in longevity in the last ten years to justify the assumption that an apparent increase in cancer could be assigned to this cause.

It is, however, no doubt true that greater knowledge and accuracy in dealing with disease lead to the result that many deaths are now properly registered as from cancer which in former years would have been ascribed to another cause. The truth of this is shown by the fact that it is not external cancers which have so

largely increased, but those in the more inaccessible parts of the body, and for that reason more difficult to recognise. So far as these cases are concerned, then, the expansion of the death-rate is apparent rather than real. At the same time, it is scarcely probable that diagnosis has been so steadily improving from year to year as to account for the annual growth of the figures. The truth appears to be that there has been a considerable increase in the deaths from cancer, but not so great as the figures would at first sight lead us to believe.

While, however, this is a matter of considerable interest to students of statistics, it must not be forgotten that it has no bearing on the amount of cancer at present prevailing. Could it even be established that the whole of the increase in the death-rate is only apparent, this would merely show that the disease was more common in past years than was supposed, and not less common now than the figures indicate; the grave fact is, that cancer was the cause in England and Wales alone of 26,721 deaths in 1900. When, in connection with this, it is remembered that the only hope of relief is to be found in the complete removal of the growth at an early stage, and that the disease is not to be cured or its progress stayed by any means at the disposal of medical science, it is evident that every possible investigation should be made which offers any hope of leading to the discovery of the cause. For it is clear that then only will it be possible to effectively treat this terrible malady. It may reasonably be hoped that in this, as in so many other cases, the discovery of the antidote will follow closely upon the identification of the poison.

The search for the cause of cancer has been considerably delayed by the view being long held that no such specific cause existed. For years the battle raged between the supporters of the rival theories of the constitutional and of the local origin of the malady, but neither party, at that time, had any suspicion of the existence of a definite external agent. The constitutionalists regarded this disease as a typical example of the result of a constitutional, i.e. hereditary, taint, and consequently took a hopeless view both as regards prevention and cure. The localists, considering malignant growths as the frequent result of a continuous local irritation, saw no reason for looking further for an explanation of their origin.

Both these views have been much modified as with the advance of medical science the conditions have been better understood. First, it has been gradually recognised how large a proportion of the deaths of individuals over forty is the result of cancer, and it has, therefore, become increasingly evident that the probabilities are in favour of a sufferer from this disease having one or more relations numbered among its victims. Further, the whole attitude of medical science towards what was known as hereditary disease has greatly changed in

recent years. While it is admitted that anatomical and physiological peculiarities are inherited which may predispose the system to the attacks of special disorders, it is now denied by many qualified observers that any disease is ever directly transmitted from parent to child. Many diseases once considered among the most marked examples of hereditary maladies are now recognised to be infectious. Consumption, long considered a typically hereditary disease, is now known to be entirely due to the action of a special bacillus introduced from without, and it is understood that the hereditary element only comes into play in so far as it may provide a suitable soil for the development of the microbe.

The result of this general change in the point of view from which constitutional diseases are now regarded is that a definite outside cause for cancer is being sought for more than ever before. By many it is thought that the disease must be of bacterial origin, and careful examination is continually being made with the view to isolating the special micro-organism, although hitherto without success. Others consider that over-indulgence in certain articles of diet, such as meat, fish, salt, or raw vegetables, invites the onset of the malady; while it must be admitted that there are some who still see the cause in mental anxiety or faulty hygienic surroundings.

I shall have to refer again to most of these theories, no one of which has found general acceptance-a matter which is not surprising when it is considered that in almost every case the opinion has been founded on a very limited number of facts. It will be easily understood that the deductions of even a highly skilled observer are likely to be erroneous if they be drawn mainly from the cases which have come under his individual observation, even if in some instances the number of these is large. A wider outlook would appear to be necessary in order to arrive at some definite conclusion, and in attempting to discover the etiology of a disease such as the one under consideration it is desirable to examine the statistics of deaths among large masses of people living under various conditions.

With this view I have recently made a series of calculations based on the recorded death-rates in most of the principal countries of Europe, as well as in some parts of the United States, and on the next page will be found the crude death-rate from cancer for various countries (mostly for the year 1900).

These figures show how greatly the incidence of cancer varies in different countries. While, however, some interesting inferences may be drawn from this fact, there are at least two reasons why the comparison of the death-rate from this disease in one country with that in another, would not give results which would be entirely trustworthy. In the first place, it must be observed that in some States the deaths from certain forms of tumour are included which in other countries are not comprised under the heading of cancer, and it is

thus not always certain what diseases exactly are classed under this heading. Secondly, the strictness of the laws concerning registration varies immensely in different States.

For these reasons I determined to take each country separately, and to investigate the incidence of cancer by examining the deathrates in its different divisions as compared with one another. The results so obtained were extremely interesting, and threw much light on the causes which underlie the development of a high mortality from malignant disease. The full tables which have been published elsewhere are too long to be included in this article, but some of the figures will be found below. At the same time, I propose to explain the mode of calculation adopted and to point out what were the principal conclusions which resulted from the inquiry.

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In each country the districts taken were those into which the State was ordinarily divided. In England, counties; in France, departments; in Germany and Austria, states and provinces were separately considered. A division into smaller units would be desirable, but could not be undertaken in this first inquiry.

In each district chosen the population, total number of deaths from all causes and deaths from cancer in one year were, except in one or two cases, obtained from official sources; and from these facts the proportion of cancer both to the population and to the general mortality was obtained. The resulting figures were in each country compared with one another, and not with those of any other State, thus avoiding the sources of error already referred to.

One other calculation was absolutely necessary in order to arrive at correct results. Cancer is essentially a disease of the latter half of life; the deaths below thirty are quite inconsiderable, between thirty and forty they are comparatively few, while from forty to

1 Cancer et Tumeur.

2 Neubildungen.

3 No official figures being available for Switzerland, the figure given is the one stated by Nencki.

↑ British Medical Journal, the 18th and 25th of April, the 1st, 8th, and 15th of May, 1903.