CANCER RESEARCH 17 



THE PRESENT STATUS OP CANCER RESEARCH 



By Dr. LEO LOEB 



BAENAED FREE SKIN AND CANCER HOSPITAL, ST. LOUIS, MO. 



IT is well known that all organisms, plants as well as animals, are 

 composed of small units — the so-called cells — in which a nucleus is 

 surrounded by protoplasm and certain special structures. Each part of 

 the animal body is formed by aggregations of different kinds of cells. 

 The skin and the cavities within the body as well as the glands are com- 

 posed of epithelial cells, the bones and muscles are produced by special 

 bone and muscle cells. Uniting the various special structures and cell- 

 layers in the body, we find the so-called connective tissue consisting of 

 special cells (connective tissue cells) and their product, the connective 

 tissue fibers. 



In the normal adult organism some kinds of cells are entirely or 

 almost at a standstill as far as their growth (increase in number and 

 size of cells) is concerned, while other kinds of cells are continually 

 propagating. However, as for each newly formed cell an old one is cast 

 off, no actual increase in the number of cells takes place during adult 

 life under normal conditions. If, however, a small part of the body, 

 e. g., the skin, is removed, the neighboring cells begin to proliferate, 

 and soon fill out the defect. We call this kind of growth regenerative. 

 Very energetic cell proliferation of course is necessary for the trans- 

 formation of an ovum into the fully developed young organism. This 

 growth, which ceases as soon as the definite organism has been formed 

 and the various organs have been differentiated, we call embryonic 

 growth. A very interesting rapid cell proliferation takes place also in 

 the uterus after the insertion of the ovum, leading to the formation of 

 the maternal placenta. 



In the normal adult organism, a definite equilibrium exists between 

 the different kinds of cell aggregations which we call tissues. Each 

 kind of cell respects the territory of the neighboring cells. Not rarely it 

 happens however that suddenly in a young or adult organism cells in a 

 certain part of the body begin to proliferate in an unusual manner ; they 

 multiply more or less rapidly. This growth can not be called regenera- 

 tive, because there was no primary defect to be filled out, and if there 

 had been such a defect the proliferation does not limit itself to wound 

 healing. This multiplication of cells leads to a definite swelling in a 

 -certain part of the body. We call it a tumor. The aggregation of 



VOL. LXXXVI. — 2. 



