How does cancer arise?

Cancer is a growing problem in Dutch society. Since 2007, cancer has been the number one cause of death in the Netherlands, with a death rate of approximately 44,000 in 2011. In that year, more than 100,000 people were diagnosed with cancer. At that time, there were also more than 430,000 people alive who had cancer or had had the disease. So it is a huge problem, and an important question is: how does cancer arise?

Cancer develops in steps

The formation of a cancerous tumor is usually a very slow process that goes through several phases. It always starts with an error in the DNA . Humans have billions of cells, and each of these cells contains a nucleus in which our DNA is hidden. This DNA stores all the information necessary for the growth, development and functioning of the human body, the so-called genetic code. If you were to pull this DNA completely apart and lay it down straight, you would have approximately one and a half meters of DNA per individual cell. With all the DNA in the body you could go up and down to the moon about 800 times. It is therefore perhaps not surprising that cancer develops, since there is a good chance that mutations will one day arise in this enormous amount of DNA.

Cell division and programmed cell death

To understand how cancer develops, it is important to first know how the body normally works. From the fertilization of the egg, cells are continuously dividing. There are also always cells dying, this is called programmed cell death, also known as apoptosis . This has a function, for example, during the development of the hands and feet, a clump of cells first forms, when it grows further, cells will grow extra fast in certain places in that clump, but cells also die. In this way the fingers and toes are created, so without this programmed cell death you retain membranes between the toes and fingers.
In the adult body, cells are still dividing continuously in many places and will die again. In some places this is more than in others. For example, the lining of the intestinal wall is continuously dividing, the cells that are formed often do not live long and are immediately replenished. Other examples are the bone marrow and the skin. There are also places in the body where cells do not or hardly divide. Nerve cells will never divide, so you are born with all the necessary nerve cells. This also applies to the muscle cells of the so-called skeletal muscles and the heart. What is important about this is that it is normally all in balance, so as many cells are added as cells die. When the balance is disturbed, you can also expect problems.

Disruption of the balance

When the balance between cell division and cell death is disturbed, cancer can develop. The cause of this is damage in the DNA. As described earlier, DNA contains all the information for the functioning of the body, including the processes that are important for cell division and cell death. If a mutation occurs in these pieces of DNA due to damage, things can go wrong. This can happen due to environmental factors, such as smoking and the UV light in sunlight. You can also be born with such an error in the DNA, in which case it is usually hereditary. Several genes are known that are related to the development of cancer. These are mainly genes that are involved in cell division and programmed cell death. Another important group is the genes that are important for DNA repair mechanisms. So when these genes become defective, the DNA cannot be repaired and mutation after mutation will accumulate. With enough mutations, the balance will be disturbed, and a cell can then divide unchecked. What exactly happens next is a very complicated process that has still not been fully elucidated.


The development of cancer is a complicated process that has not yet been fully elucidated. It starts with damage to places on the DNA that are important for cell division and cell death, or in genes that are involved in the repair of DNA damage. When sufficient mutations have accumulated, the cell can divide uninhibitedly, including the daughter cells. This process continues slowly until a tumor develops, which will eventually cause complaints. With more knowledge of the origins of cancer, treatments can be developed or cancer can even be prevented. This knowledge is also the basis of the population screening for cervical cancer. A smear is used to obtain a group of cells that can be viewed under a microscope. Pre-cancerous lesions can be recognized and intervention can be performed relatively early. This underlines the importance of knowledge about the pathogenesis of cancer.

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