While cancer is no respecter of persons, and affects all, rich and poor, old and young, male and female, there are some interesting features regarding the disease as it occurs under various conditions which are worthy of consideration.
We have seen in the former lecture that cancer is not a definite something, from without, that attacks the human frame, but that it is only a faulty development and action of certain body cells, which were once normal, with a steady decline in bodily health which tends to a fatal issue in a very large proportion of those once affected with the disease.
We have seen that the cancer patient, both in the very earliest stages and during the whole period of the disease, gives evidence of departures from the ideal normal life, and presents functional disorders of various organs, with derangements of metabolism; these point to errors of nutrition, which latter are of significance in connection with the development and continuance of the malignant disease. The conclusion offered was that cancer is a medical affection, due to systemic causes, and that the simple surgical excision of a certain diseased portion cannot be expected to check or remove such a malady, or to prevent recurrence. And this has been abundantly demonstrated by the history of the disease, with its steadily increasing mortality under increasingly active surgical treatment during the last fifteen years, as was shown in my former lectures and will be further illustrated later.
Recognizing, then, that cancer is a great and widespread disorder of nutrition, let us consider some of the facts regarding its extension and some of the influences concerned in its production.
Sex.—Cancer is much more frequent in females than in males. In the United States Mortality Reports for 1914 there were 31,138 females to 21,282 males; thus, in a total of 52,420 deaths from cancer 59.4 per cent were in females, with a preponderance of 9,856. This excess is largely due to cancer of the breast, from which there were 5,423 deaths, and cancer of the female genital organs, causing 8,152 deaths, of which 7,470 were from cancer of the uterus.
The death rate in males, however, seems to be increasing of late years; in the United States in 1912 males formed 39.7 per cent; in 1913, 40.1 per cent; and in 1914, 40.6 per cent. In England, according to Williams, the proportion of males to females is increasing much more rapidly. This greater mortality of males is due to the greater number of deaths from cancer of the stomach and liver, buccal cavity, and skin. In 1914 there were 19,889 deaths from cancer of the stomach and liver, or 37.9 per cent of the whole number; of these 10,122 were in males to 9,767 in females, or an excess of 355 males, whereas in 1912 the females were 87 in excess. In the United States the cancer death rate for males has increased since 1901 31.8 per cent and for females 25.3 per cent.
Age.—Carcinoma is exceedingly rare under 20 years of age, most malignant tumors at that period being sarcomata. After 25 the number of deaths from cancer about doubles each five years up to 40, and then increases steadily, until the actually greatest number of deaths, 6,909 (3,071 males, 3,838 females), occurred between 60 and 64 years of age, after which they decreased steadily; there were 267 deaths at 90 and over, 8 of them being 100 years and over. At no period did the deaths of males exceed that of females, and from 35 to 39 years of age the latter were almost three times that of males.
Occupation.—Many attempts have been made to trace the influence of occupation upon the incidence of cancer, but thus far very little of practical interest has been demonstrated; the difficulties concerning this investigation are immense, owing to absence of essential and accurate data. There have been many lists presented, but few of which agree as to details, and all need to be corrected as to the proportion of those living at different ages. There is also the question as to the effect of local or general agencies; thus, as to the result of local injuries on the skin, and also in regard to other agencies, whatever they may be, which produce internal cancer; for tables of occupation do not generally refer to sex, age, or location of the disease.
First, to dismiss the question as to the direct result of local injuries in inducing cancer of the skin, which, at the most, caused only 3.7 per cent of all cancer deaths in 1914, we may cite a few instances in which this appears to be pretty well established.
The occurrence of epithelioma as a direct result of repeated and protracted exposure to X-ray is familiar to all, and is particularly interesting because it occurs commonly among younger persons, and at a time of life when epithelioma is rare; and especially also because the X-ray is constantly effective in curing epithelioma. The rarity of epithelioma resulting from X-ray, considering the enormous amount of exposure which must have occurred in making and using X-ray tubes, implies, however, that there must be some other cause also at work. It has been urged, therefore, that the skin tissue being altered and weakened from repeated and protracted exposure to X-rays, more readily falls prey to some of the chemical or other irritating agencies which have been observed to be followed by epithelioma.
Time does not permit even a mention of the various elements, which are many, that have been credited as excitants of cutaneous epithelioma; but brief allusion may be made to one which formerly attracted much attention, mainly in England; this refers to chimney-sweeps cancer, the mortality from which was at one time at least 5 times greater than that from cancer in males generally, at the same age. This is now, however, of relatively infrequent occurrence, owing to the adoption of other methods of cleaning chimneys. The epithelioma, which more commonly developed on the scrotum, was believed to be due to the long continued irritation caused by the constant presence of soot on the part; other products of combustion and tar derivations have also been accredited with the same result.
The question of the influence of occupation along other lines is really more interesting, because more obscure; but a careful study of available data tends to show the correctness of the thesis on which my former lectures and these are based. This, as you know, is that our so-called advancing civilization, with all its errors of life, in many directions, is at the bottom of the steady increase in the mortality from cancer.
One of the most interesting contributions to this was the investigation made by Dr. Latham, Registrar-General, in a study of cancer returns in England; this showed that the mortality from the disease was more than twice as great among well-to-do men having no specific occupation as among occupied males in general, the respective mortality ratio being 96 for the former and only 44 for the latter. The same observation has been made elsewhere.
Moreover, it is reported from several reliable sources that the death rate from cancer in many cities is proportionately greater among the rich and those in easy circumstances than among the poor, wage-earning element of society. This would seem to show that occupation in general acts favorably against the development of cancer. This fact is quite understandable when we consider that those engaged in active work are less liable to suffer from the effects of gluttony and indolence, with their concurrent metabolic disturbances, than the well-to-do with ease and luxurious habits. It is remarkable, however, that in asylums, homes for the aged, prisons, convents, monasteries, etc., where the inmates are relatively unoccupied, many writers confirm the fact that cancer is very seldom seen; but this again is explained by the simple and frugal diet enforced, with very little meat, which agrees with our thesis.
Statistics from life insurance companies show that cancer is decidedly more common among persons of over-weight than among under-weights.
In regard to the occupations of those dying from cancer it is interesting to note that standing among the highest per 100,000 population, in English statistics, come brewers, inn-keepers, and butchers, whose metabolism can be greatly disturbed by alcohol and meat; also indoor servants are more apt to be affected, while those of more or less sedentary occupation, such as school teachers, clergymen, physicians, and tailors, likewise stand very high on several lists. On the other hand, those engaged in active physical exercise, such as miners, farm laborers, carpenters, blacksmith, mail-carriers, and others, are among those least frequently attacked.
Race.—Cancer has been observed in every race, though the proportion of cases is observed to vary greatly among different peoples; but it is interesting to note that it is universally agreed by those that have studied the subject that the difference in frequency relates very largely to the degree of civilization involved. The blond Nordic race, however, seems to be more susceptible to the disease than the darker races, originally of Asiatic origin; and it is the former who have pushed forward modern civilization, with all its errors of life.
Thus cancer is everywhere reported to be rare, and sometimes almost absent, in primitive, uncivilized peoples, but it has been repeatedly observed, in many localities, that as these same people mix with Europeans and adopt their diet and mode of life, cancer is sure to increase, until its frequency often about equals that in their highly civilized neighbors. I went over this matter pretty fully in my former lectures and cannot dwell on it now, or give examples. I can only emphasize the fact that this furnishes a strong support to the contention that cancer depends upon disorders of metabolism, which are certainly increasing under the various elements which compose what is called advanced civilization.
Climate and Locality.—There is no evidence to prove that climate has any influence in the production of cancer, nor is it affected by locality; the disease occurs in hot, warm, temperate, and cold climates, and in every possible location on the earth. But it is undoubtedly most prevalent in temperate regions, for the reason that it is in these that modern civilization, with all its faults and foibles, is most highly developed.
The subject of the topical distribution of cancer, or its occurrence in certain regions, has been the subject of much controversy in England and France especially, and to read certain statements one would be inclined to believe that certain telluric conditions were of influence in its production, as along certain water courses, etc. But a more careful analysis of all these statements shows that such elements can act only as contributing causes, as, for instance, through a rheumatic influence, which is known to be found in so many cancer patients.
The same may be said in regard to so-called “cancer houses” concerning which there are still occasional references. A careful investigation of these houses has commonly found them to be old, moldy, damp, badly ventilated, and otherwise unsanitary; also that such old houses are commonly tenanted by old people in succession, so that there are more at a cancer age to be affected. With our present knowledge of the causes which lead up to cancer we cannot but conclude, therefore, that the occurrence of the disease in groups, with some apparent connection, has been only the result of all living under the same conditions of ill health, including wrong diet, etc.; for we know that cancer is not contagious or infectious, and there is no other reasonable explanation which can be sustained.
Food and Mode of Life.—In my former lectures I presented very fully the evidence that cancer was certainly a disease of civilization, its frequency and mortality advancing steadily in proportion as various tribes or peoples, previously exempt, have come more or less under its influence and adopted its manners and customs.
When we speak, therefore, of the influence of food in the production of cancer it must be understood that it is not claimed that the diseased process depends wholly and exclusively on the character of the food, including drink, taken. In my former lectures I tried to show that cancer was the result of a deranged nutrition, and we know that one of the greatest elements in inducing this latter is erroneous metabolism, depending again on the diet, to a very great extent. In a later lecture I shall hope to develop this subject further, and indicate more completely than on the previous occasion, the elements of causation and the measures which can be successful in overcoming the disease.
In order to understand rightly the rôle which diet may have in the production of cancer I may have to briefly repeat, more or less, some of the matters brought forward in my lectures two years ago, and shall treat of the correction of diet in a later lecture.
We understand, of course, that the body is a vast laboratory, wherein, by exceedingly complicated processes, material from the outside world is appropriated to the needs of the economy, and after its use is cast out in very different and elementary forms. To effect the various changes necessary in this material we have a very considerable number of what are called organs of secretion and excretion, whose functions are combined and correlated in a marvelous manner, which is even yet very imperfectly understood.
The actual biochemical processes by means of which the transformation of external food elements into living tissue and force, physical and mental, takes place are known as: 1. Anabolism, or the process of assimilation of nutritive matter and its conversion into living substance; and 2. Catabolism, or the breaking down of complex bodies of living matter into waste products of simpler chemical composition. These together constitute 3. Metabolism, or the sum of the chemical changes whereby the function of nutrition is effected. The actual procedure by which most of these activities is carried on is one of oxidation, by means of the oxygen supplied largely by the lungs, which constitutes about 65 per cent of the human body.
Now to make up for the daily waste of the other 15 elements, which form 35 per cent of the body tissues, and to support the necessary activities of the system, mental and physical, it is necessary every day to take a more or less even supply of substances, which we call food and drink, which should contain about the proper proportion of the requisite bodily components. Under normal conditions of healthy living the appetite ordinarily serves as a proper guide for health in man and beast, serving to regulate the selection of material to preserve the balance of nutrition. But man especially has temptations to gratify the taste, which is quite a different thing from satisfying the appetite, and all are familiar with the many forms of disaster and disease which arise from gratifying the taste in food and drink; moreover, the temptations to this seem to increase continually with the so-called refinements of civilization.
The actual nutritive elements which are required are relatively few, and fall mainly under three classes: 1, Protein; 2, Carbohydrates; and 3, Fats. Of these the latter two furnish most of the 18 per cent of carbon in the body, and the animal or vegetable protein furnishes the nitrogen, which forms only about 3 per cent of the body tissues: all these substances are, of course, used up constantly in providing heat and energy, physical and mental, day by day, the protein being concerned chiefly in replacing wasted tissue. The combustion of the carbohydrates and fat is relatively simple, and the waste products pass off harmlessly, mainly by the lungs, as carbonic acid and water.
But the course of the protein, or nitrogenous and sulphur and other mineral elements, is quite different. In the anabolism and catabolism of protein there are a vast number of intermediate changes, and various products are elaborated which we know to be of great significance in the system, and which when imperfectly completed are the source of much disorder and disease in the economy. Of this the gouty state is a notable example, with a long list of secondary disorders.
But few realize, however, that cancer is another disease which is quite as striking in its relation to faulty nitrogenous and sulphur metabolism. In my former lectures I developed this subject pretty fully and need not repeat it here, but could adduce more recent proof, did time permit. Suffice to remind you that many independent observers have recorded very important and significant errors in the nitrogen and sulphur partition in cancer, both in its early and late stages, some of which I have verified in hundreds of volumetric urinary analyses. As these errors are made to disappear by proper dietary and medicinal treatment the carcinomatous lesions have steadily improved, and in many cases have disappeared entirely, as I hope to demonstrate in a later lecture.
We must, therefore, accept the fact that cancer has very close relations to the elaboration of protein in the system, and the rational deduction of this is that an overconsumption of nitrogenous food has something, if not everything, to do with the production of cancer. As yet we know little or nothing in regard to actual cancer-genesis; no one has ever demonstrated, and probably no one ever will demonstrate, the absolute beginning of the change in some normal cell or cells, in the breast or elsewhere, which eventuates in their taking on the rampant or malignant feature which we call cancer. But this change does occur, and though the exact alterations in the polarity of the cells and the disturbance of their centrosomes and nuclei, which have been described, may not be perfectly understood, there is some definite cause for their occurrence. Some have suggested the hypothesis that the mononuclear leukocyte, by conjugation with disturbed cells, gives them an abnormal reproductive power by which they eventually develop the tumor and invade other tissues. But back of all this there is still some activating cause, which is found in the fluids which bathe every tissue, namely the blood and lymph, which we shall see later are deranged in cancer.
The fact that with innumerable injuries occurring everywhere and at all times cancer develops from them very rarely, should teach us something. We must conclude, therefore, that there is some constitutional condition, or rather some state of the blood, which nourishes the cells and which favors this continued malignancy—some fuel which feeds the malignant process and at the same time induces a progressive lowered vitality, ending fatally. For we have already seen in these and former lectures that the local lesion which we call cancer is but one manifestation or result of a pernicious anemia, which, if not checked, may end life in a relatively short time.
As cancer is not contagious or infectious, this anemia, with all its concomitants, including the local trouble which we call cancer, must be autotoxic, and evidence is strong that it is of a nitrogenous origin. We look naturally, therefore, to see if there can be found any relationship between an augmented consumption of protein-bearing food and the steady increase in cancer mortality which is reported on every side.
England has furnished more fully and for a longer period than any other country the mortality and dietary statistics of its population, and from these we can learn a great deal of value in our study.
According to a carefully prepared table by W. R. Williams showing the total population in England during the years from 1840 to 1905, cancer deaths had increased from 17.7 per 100,000 population in 1840 to 88.5 in 1905, or five times in numbers, and in 1913 there were 105.5 deaths from cancer in 100,000 population. During this time the meat consumption had more than doubled, to 130 pounds per capita in 1904; so that, according to Williams, it is estimated that among the adult well-to-do population the per capita meat consumption was from 180 to 330 pounds per year, in addition to large quantities of game, poultry, eggs, fish, etc.
The United States Report of the Meat Situation, 1916, also furnishes some valuable information to aid in this inquiry.
The Argentine Republic stands next in the consumption of meat, with 140 pounds per capita, and with a cancer mortality of 91 per 100,000 in 1900.
The United States comes next, with a per capita consumption of meat at 201.1 pounds in 1909 and a death rate from cancer of 73.8 per 100,000 in that year, which, as previously stated, was 79.4 in 1914 and 81.1 in 1915.
New Zealand exceeds the United States a little, with a meat consumption in 1902 of 212.5 pounds per capita, and an increase in cancer mortality from 32 in 1877–1888 to 60 per 100,000 in 1900 and 71 in 1903. This increase is mainly among British and other immigrants, whereas the aborigines, living simple lives, are seldom affected.
Australia stands first in the consumption of meat, with the enormous rate of 262.6 pounds per capita in 1902, and the increase of deaths from cancer there is most striking. In 1851 the death rate per 100,000 living was 14, in 1900, 62.6, and in 1913, 75 per 100,000 living. The most striking difference is exhibited between those who are native born, who in 1900 had a cancer death rate of only 22 per 100,000, while the British born had a mortality from cancer of 203, or nine times as great; a still higher ratio was found among immigrants of other nationalities. Those who have written there on the subject ascribe this proclivity to cancer to the gluttonous habits of immigrants, who have meat for breakfast, lunch, dinner, tea, and supper (MacDonald, Williams).
Italy, consuming the least quantity of meat, 46.5 pounds per capita, in 1901, has the lowest cancer death rate, but the present meat consumption cannot be learned. In Italy, however, the mortality from this disease is steadily rising, from 50.9 per 100,000 in 1860 to 1900 to 63.6 per 100,000 from 1906 to 1910.
But, as I have tried to show you all along, it is some derangement of metabolism which is at the bottom of neoplastic growths, and that derangement is not necessarily due to any one single cause, as diet. There are other elements of disturbance besides the nitrogenous malassimilation which is due to the intake of an excessive amount of the proteid of the animal kingdom; for cancer is said to have been seen in vegetarians, although I have never met with such a case. We know, however, that some or many articles from the vegetable kingdom, such as the pulses and some nuts, contain a very large proportion of proteid; thus dried peas contain 21 per cent, haricot beans 23, lentils 23.2, dried lima beans 26.4, soy bean flour, 39.5, butternuts 27.9, black walnuts 27.6, peanuts 25.8, and almonds 24 per cent of proteid, all more than is contained in beef and mutton. Thus a large supply of any of these might produce the same error in the blood stream as that induced by meat.
In my former lectures I pointed out also that coffee and alcohol were found by statistics and clinical experience to have a prejudicial effect on cancer, and therefore must be considered as elements in its production. In a later lecture I shall deal more specifically with these matters, in reference to the prophylaxis and treatment of the disease.
At the present time I will only remind you of what I have so often said before: that it is the complex of modern civilization, with all its temptations and errors in regard to eating and drinking, and living, including the nervous strain felt everywhere, that in some way produces alterations in nutrition which account for many of our diseases. This operates through the blood current, which ministers in such a way to the tissues that under some slight provocation a heterologous growth of certain tissue cells occurs, with malignant tendencies, instead of the normal homogeneous and stabile structures which compose healthy tissues; and this departure from normal cell action we call cancer.