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How and why does cancer occur?

Cancer is a genetic disease - it is caused by changes in the genes that control the function of all cells in the body, especially their growth and division. However, this does not mean that only the genetic material we inherited from our ancestors is important for the development of cancer. Genetic changes that cause cancer can be inherited from parents, but more often occur during life as errors in cell division or DNA damage caused by environmental influences (for example, chemicals from cigarette smoke or ultraviolet radiation from the sun). Overall, it is believed that only 5-10% of cancer cases are the result of genetics alone. Most malignant diseases are caused by the interplay of environmental factors and genetics, so that we ourselves have a significant influence on the risk of disease development. It can be said that the cancer of each individual patient is special, i.e. it contains a unique combination of genetic changes and even different cancer cells within the same tumor masses are not all equal. This happens because during their growth cancer cells accumulate additional genetic changes. In general, cancer cells have a large number of accumulated mutations, especially compared to normal cells. At the same time, some of these mutations have nothing to do with the development of cancer.


cell cycle, cell cycle

Figure 1. Illustration of the influence of proto-oncogenes in the development of cancer cells. If these genes become too active, instead of regulating normal cell growth and division, they can lead to uncontrolled cell division and ultimately to cancer.



"Driver" mutations. Genetic changes (mutations) that are associated with the development of cancer involve one of 3 main types of genes - proto-oncogenes, tumor suppressor genes or DNA repair genes. Mutations of these genes are called "driver" mutations, because they are directly related to the development of cancer. Proto-oncogenes are genes that control normal cell growth and division. When these genes change, they can become overactive, allowing cells to grow and survive when they shouldn't, and are then called oncogenes. Tumor suppressor genes are also involved in cell growth and division, and cells with mutations of these genes can divide uncontrollably. Unlike proto-oncogenes, they can lead to cancer not when they are more active, but when their function is reduced. DNA repair genes repair DNA damage that occurs during division. DNA damage is not rare, but with the normal function of these genes, they are regularly repaired. Cells with mutations in DNA repair genes easily accumulate additional mutations. which can ultimately lead to the development of cancer.

​Additional points of interest


It is interesting that animals can develop cancer, but some of them, like for example elephants, have a very low risk. The reason is that elephants have as many as 38 modified copies of the gene for P53. s of the other side, have only 2._11100000-0000-0000-0000-00000000000111_navenate gene is discovered in 1979 and the first is a discovered tumor suppressor gene. Its role is to prevent the formation of tumors by stopping cell division, activating DNA repair enzymes or causing apoptosis (programmed cell death) if abnormal cells appear.


Continue reading: < a href="https://www.onkologija.net/post/kako-se-rak-%C5%A1iri-i-za%C5%A1to-je-sletomslan" target="_top">How does cancer spread?

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