In healthy tissue cells often go lost, and it is of the utmost importance that is compensated for by the process of cell division, this loss of cells. If we are talking about a cancer, we usually have an image of a mass of rapidly dividing cells, but that is not correct.
The tumor that developed somewhere in the body, usually consists of a central body, to which is fixed a number in the surrounding tissue ingrowing, branched appendages. The whole image is indeed reminiscent something to the construction of a crab. Therefore, the latin Cancer may be the origin of the name cancer. The process begins when a single cancer cell will behave differently, while the tumor is the end result of this process.
When we talk about a tumor, we usually have in mind the image of a multitude of rapidly dividing cancer cells but that is not correct. Inside the cancer cells divide probably even slower than the cells of normal tissues. Despite the phenomenon that the divisions follow each other more slowly in the tumor than to normal cells, the tumor will nevertheless in volume, and the healthy tissue. The difference between normal tissue and tumor tissue consists in the fact that the proliferation rate is controlled in such a way to healthy tissue, that the number of newly formed cells is just sufficient to replace the number of lost cells, while within the tumor to continue to share the cancer cells, even if it is not required. It is as if the tumor cell are constantly induced to divide. If then is converted somewhere in the body an ordinary cell in the body by one or other cause in a cancer cell, is one of the most important features, that the divisions continue to monitor each other. The time between two successive divisions is between 40 to 80 hours, a period that applies to both the tumor cell and a normal cell in the body.
In healthy tissue cells often go lost, and it is of the utmost importance that is compensated for by the process of cell division this loss of cells. In a period in which occurs a smaller loss of cells, a control mechanism must ensure that the time is extended between two divisions.
Also, the tumor cells frequently lose. Cells that are in locations within the tumor, where the circulation is insufficient, die off. Other cells have been changed in the cancer process in such a way, that they are no longer viable, while again releasing other cells of the tumor, and can be brought by the blood stream to other parts of the body.
Of healthy tissue, we can say that the cell loss amounts to 100% with respect to the number of cells is newly formed. During the cancer process, however, the cell loss is from 95 to 99%, so the new formation is then greater than the cell loss. The closer the cell loss approaches 100%, the slower growing tumor. It is therefore not important to know how many cell divisions per unit of time, there take place, because that says little about the growth of the tumor. To display on the growth rate of the information has been entered the tumor-doubling time, and the doubling time is much longer than the time between two divisions.
The doubling time is usually between 100 and 200 days, and during this period the volume of the tumor is twice as large. With a rapid doubling time of 125 days, for example, the tumor doubling himself three times per year. The cancer process begins with a single cancer cell, and after three doubling times is out of this cell, so after a year, create a group of eight small cells. In this case, if one continues the doubling time of 125 days, the arithmetic last 10 years, before a tumor has grown out of that one cancer cell, which starts to fall due to its size. If a tumor is detected in such a case, the patient has at least ten years cancer.
With a doubling time of 100 days, it will take more than 8 years before the position of a billion cells within the tumor. With this number of cancer cells, the tumor has a diameter of about 1 cm, and only at this size it is possible that the tumor is detected. In cancer, we have the phenomenon of exponential growth, and we let a tumor of 1 cm diameter and 1 gram weight evolve with the doubling time of 100 days, the tumor within the 3 years to reach a weight of 1 kg.
Although it seems that tumor cells are programmed to survive, there are many promising new treatment methods. But what can they, when they come?
When the tumor, though growing, would only increase in size, cancer would not be such a big problem. As a result of the fact that at a certain point in time in the development, the cancer cells will release tumor, cancer will only become a problem of format. Each loosened little cell can, in principle, again to form a new beginning of a tumor, which can cause daughter tumors at all sites in the body. This process of uitzaaïng called metastasize. Therefore, it is important to know at what time a tumor has a tendency to go off punches cells.
For most cancers, this has unfortunately already spread in a remarkably early stage place, although there are big differences between the various types of cancer. Due to the fact that lung cancer is already at a very early stage cells released into the bloodstream, lung cancer is one of the most aggressive cancers. Even earlier metastatic tumors begin to let all cells loose when the number of cells is increased to 4000, but usually only one will go into account as metastases to keep the number of cells is greater than 50,000. The tumor is then about 4.5 years old and has a diameter smaller than 0.1 cm.
As the tumor volume increases, so does the chance of uitzaaïngen. We assume that a cell that has become detached from the tumor anywhere within the body finds a suitable place. If the cancer cell itself then goes to develop with a doubling rate equal to that of the original tumor, it will be understood that the presence and location of uitzaaïngen is a very tricky business. After all, if the mother tumor reaches the size that it can be detected, so 1 cm in diameter, then the tumor is 8 years old. The uitzaaïngen, however, only 3.5 years, and they still contain no more than 5000 cells. The format is then only a needlepoint large and the probability that it is detected is zero.