In adult individuals, under normal circumstances there is a balance between formation and destruction of tissue. Tersifat tumor growth mostly by a positive balance: more cells than cells that lost the case. But the growth rate is generally smaller than the normal growth rate of fetal tissue or tissues in the regeneration.
The time needed by tumors to increase the volume of two times can vary from a few weeks to several years, depending on the type of tumor and its condition. This volume increase depends on: elapsed time between two cell divisions, intermitotik phase, the composition of the population of cells (not all cells divide or split up just as fast) and the number of cells that die in a given period. This last factor is perhaps the second most important.
When the cell cycle, mitotic phase plus the phase intermitotik, plays an important role in the speed of growth. After dividing cells, the cells in the G1 phase children come, the time period of the cell-specific function, eg protein synthesis.
From the G1 phase to the S phase of the cell comes, when the cells begin to synthesize DNA, the genetic material in preparation tuck split. Before cells divide (M phase), there is still the G2 phase. At this time the nucleus contain twice as much DNA. The minimum time a cell cycle, measured on cells in tissue culture, approximately 16 hours.
This time for the in vivo intestinal epithelium is 12 hours, 21 days epidermis, liver 160 days. When S phase and G2 phase roughly constant; great variability, which are also in tumor cells located in the G1 phase. There are cells that are always or years are in the G1 phase, the cell-cell differentiation-specific functions.
As will be explained in the following chapters, the various phases are very different sensitivities to exogenous influences, such as X-rays that ionize and sitostatica. Many conditions can affect the growth process; perhaps most importantly, the tumor vascularity of the surrounding tissue.
Angiogenesis of the tumor and the area around the tumor may be influenced by the products of tumor cells. Much attention is given to the substance-specific growth inhibitor to tissue which is found by Bullough and are called 'chalon' '. Tumors contain and produce '' chalon 'fewer than tissue from which the tumor had been.
Investigations by Collins et al and Breur indicate that certain tumors such as metastases in the lungs, takes a very constant to multiply the volume up to two times. Can be calculated that the contrast of the tumor cells with an average volume of tumor cells, it takes 30 times folding to reach a volume of 1 cm.
When in a state of time for one-time folding is 100 days, and this remains constant, then for 30 times the folding takes approximately 8 years. Folding within the next 10 times (10 X 100 days) volumes will rise from 1 cm to about 1.000 cm.
So it is clear that the tumor had actually been there long before we were able to demonstrate the methods and diagnostic tools are very sharp though. And throughout the period of clinical observation, diagostik and new therapies that cell division takes place between the 30th and 40th.
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