Predisposing Causes

Age

Certain tumors apparently bear a distinct relationship to the age of the individual. Before thirty years the sarcomata are most likely to appear; after that period, the carcinomata.

Sex

On account of the frequent involvement of the female genitalia women are much more commonly the victims of cancer than men.

Heredity may have some influence, as it has been found that carcinomata are more common in some families than in others.

Occupation, as in chimney-sweepers and in paraffin-workers, who seem to frequently suffer from carcinoma. Probably the result of chronic irritation due to a lack of cleanliness.

Morphology

Tumors may differ greatly in the following respects:

Size

They may be of any size, from microscopic to weighing 275 pounds, as reported by Delameter.

Shape

According to their shape tumors are called nodular when spheric, tubercles when projecting as a rounded body above the surface of an organ, flat or tabular when rising as a comparatively level elevation.

When the growth is connected to its original site by a stalk or pedicle it is called a polyp. When the surface is very roughened and irregular the tumor may be termed a cauliflower or dendritic growth.

If like a mushroom with a narrow stalk and a broad head, it is termed a fungus.

Color

The color of a growth depends upon the nature of the tissue of which it is composed, upon the amount of blood present, and the presence of pigment. It may also be modified if degenerative processes have taken place.

Consistency depends upon the structure of the growth and upon the presence or absence of degenerations. If of bone the tumor will be very hard; if of mucous tissue, very soft.

Number

Tumors may be single or multiple, there being usually a single primary tumor with several secondary ones if the growth is malignant, these latter being of the same type as the primary. There may, however, be hundreds of primary tumors, as in cases of fibroma molluscum. Sometimes there may be several primary tumors of different histologic types.

A recurrent tumor is one that recurs at the place from which it was removed.

According to the arrangement, tumors may be typical, hemo-plastic, or homologous when they resemble the tissue from which they arise; atypical, heteroplastic, or heterologous when they differ.

If made up of a simple tissue they are called histoid tumors; if of a combination, attempting the formation of an organ, organoid; and when containing portions of all three blastodermic layers, teratoid.

The blood-vessels, which always originate from pre-existing vessels, may be greatly increased in number, telangiectatic; in size, cavernous; or unusually arranged, plexiform. These may be greatly decreased in number, thereby favoring secondary changes, or their walls may be imperfectly formed, giving rise to hemorrhages. Capillaries are commonly absent. Lymphatics are usually present, but the nervous supply is very poor, as a rule.

The growth of a tumor is independent of that of the individual. It may continue even if the normal tissues are being sacrificed for it. A lipoma will grow although the patient may not be getting sufficient nourishment to carry on the normal functions of the body.

It may be either central expansion, as is the case in benign growths, or peripheral infiltration, as in the malignant forms. The latter also increase by means of the central expansion.

As the blood-supply of tumors is usually poor, they frequently undergo various forms of degeneration, as pigmentation, calcification, fatty, hyaline, colloid, and mucoid metamorphoses; necrosis and ulceration.

According to their effect upon the individual a new growth may be either benign or malignant.

Benign growths do not affect the patient except as they may press upon vital structures or undergo degenerative processes.

They are usually circumscribed, encapsulated, do not give metastases, and do not recur after excision.

Malignant tumors are those that through their own influences tend to bring about the death of the individual. They are not circumscribed nor encapsulated, cause cachexia, probably toxic in origin, give metastasis, and recur after excision.

Metastasis refers to the extension of the primary growth by the transference of malignant cells to other parts of the body. In carcinoma this takes place, as a rule, by means of the lymphatics. As the original tumor increases in size its cells penetrate the surrounding tissues, and on account of the decreased resistance, tend to grow along the lymphatic spaces. In this way distant growths may be directly connected with the primary focus by means of these strands. This is frequently spoken of as the permeation method. As the tumor extends, it is the neighboring lymph-nodes that first show secondary involvement. The extension continues until a chain of lymph-nodes is attacked. It is also very probable that extension by means of the blood may occur indirectly in carcinoma. The tumor cells may gain entrance to the thoracic duct and thus get into the circulation. They then usually lodge in the liver and give rise to new masses. Under other conditions, such as necrosis and ulceration, the cancer cells can enter directly into the blood.

In sarcoma extension takes place only by means of the blood, the walls of the vessels being very incomplete and easily allowing the entrance of tumor cells.

Death may be caused by tumors -

1. Pressing upon vital organs.

2. Invading vital organs and causing degeneration.

3. Hemorrhage resulting from ulceration and degeneration.

4. Absorption of poisonous products.

5. Secondary infection.

6. Exhaustion due to the tumor using up so much nutrition for its own benefit.