The Growth Of The Body : Part 2

Disease and its Causes
by William Thomas Councilman, M.D.

(Page 4 of 14)

These new tumors are similar in character to the original tumor, and really represent parts of it in the same way that all the Baldwin apples in the world are parts of the original tree which was found in Baldwinville many years ago, and as all the Concord grape vines are really parts of the original vine. It has been estimated that if all the growth capacity of this mouse tumor were availed of by the successive inoculation of other mice, a mass of tumor several times the diameter of the sun would grow in two years. The condition of the individual seems to exert no influence upon the growth of the tumor. Growth may be as rapid when the bearer is in a condition of extreme emaciation as it is when the bearer is well nourished and robust.

Those tumors which grow rapidly and invade and destroy the surrounding tissue are called malignant tumors or cancers, but in a strict sense no tumor can be regarded as benign, for none can serve a useful purpose. A tumor after a period of slow growth can begin to grow rapidly. Tumors may arise in any part of the body, but there are certain places of preference particularly for the more malignant tumors. These are places where the cells naturally have a marked power of growth, and especially where growth is intermittent as in the uterus and mammary gland.

Little is known in regard to the influence of inheritance on the formation of tumors. Study of the tumors of mice show a slightly greater susceptibility to tumor formation in the progeny of mice who have developed tumors. Studies of human families seem to show that heredity has a slight influence, but in the frequency of tumors such statistical evidence is of little value. The question of inheritance has much bearing on the origin of tumors. If the tumor is accidental and due entirely to extraneous causes, inheritance is not probable; but if there is some predisposition to tumor formation in certain individuals due to some peculiarity, then inheritance may exert an influence.

The question as to whether tumors are an increasing cause of disease is equally difficult of solution. The mortality statistics, if taken at their face value, show an enormous increase in frequency; but there are many factors which must be considered and which render the decision difficult and doubtful. Tumors are largely a prerogative of age, and the increased duration of life which preventive medicine has brought about brings more people into the age when tumors are more common. Owing to the greater skill in the diagnosis of tumors, especially those of the internal organs, they are now recognized more frequently and more deaths are correctly ascribed to them. Deaths from tumors were formerly often purposely concealed and attributed to some other cause.

No age is immune to tumors. They may be present at birth or develop shortly afterwards. The age from five to twenty years is the most free from them, that from forty-five to sixty-five the most susceptible, particularly to the more malignant forms.

A tumor is a local disease. The growing tissue of the tumor is the disease, and it is evident that if the entire tumor were removed the disease would be cured. This is the end sought by surgical interference, but notwithstanding seemingly thorough removal, the tumor often reappears after an interval of months or years. There are many conditions which may render the complete removal of a tumor difficult or impossible. It is often impossible to ascertain just how far the tumor cells have invaded the neighboring structures; the situation of the tumor may be such that an extended removal would injure organs which are essential for life, or at the time of removal the tumor cells may have been conveyed elsewhere by the blood or lymphatic vessels.

Successful removal depends mainly upon the length of time the tumor has been growing. At an early stage even the most malignant tumor may be successfully removed. It is evident from this how disastrous may be the neglect of proper surgical treatment of a tumor. The time may be very short between the first evidence of the presence of a tumor and the development of a condition which would render complete removal impossible.

The effect of a tumor upon its bearer depends upon its character and situation. Pain is very commonly present, and is due to the pressure which the growing tumor exerts upon the sensory nerves. Pain may, however, not be present or appear only at the last. A condition of malnutrition and emaciation often results due to the passage into the blood of injurious substances formed in the tumor, or to the destruction of important organs by the growing tumor. The growth of a tumor in the intestine may obstruct or close the canal and thus interfere with nutrition.

The cause or causes of tumors are unknown. We know that the tumor represents essentially an abnormal growth, and that this growth is due to new formation of cells. In certain cases the tumor repeats the structure of the organ or tissue in which it originates, in others it departs widely from this; always, however, its structure resembles structures found in the body at some period of life. The tumor cells, like all other cells of the body, grow by means of the nutriment which the body supplies; they have no intrinsic sources of energy. The great problem is what starts the cells to grow and why the growth differs from that of normal tissue, why it is not regulated and coördinated as are other forms of growth. When a small piece of the skin, for instance, is cut out growth as rapid as that in tumors takes place in the adjoining cells, but it ceases when the loss is restored. The same is true when a piece of the liver is removed.

Various hypotheses have been formed to explain the tumor, all of them of interest, and they have had great importance in that the attempt to prove or disprove the hypothesis by continued observation and experiment along definite lines has produced new knowledge. The various theories as to cause may be divided into three heads.

The parasitic theory. This supposes that a living parasite invades the body, and by its presence excites the cells of certain tissues to grow in tumor form. It is known that active growth of the cells of the body can be excited in a number of ways, by chemical substances such as certain of the coal tar products, and that it often takes place under the influence of bacteria. It is further known that parasites can produce tumor-like growths in plants. The large, rough excrescences on the oaks are produced by a fly which lays its eggs in or beneath the bark, and the larva which develops from the egg secretes a substance which causes the cells about it to multiply, and a huge mass is formed which serves the developing insect for both food and protection. Large tumor-like masses are formed on the roots and stalk of cabbages as the result of the invasion of the cells by a minute organism: the tumors of olive trees are due to a bacterium; the peculiar growths on cedar trees, the so-called "witches' brooms," are produced by a fungus, and there are many other such examples.

New York, Henry Holt And Company.
London, Williams and Norgate, originally published 1913